Impressum Parametric_Ferrante_Rackoff.thy

(*  Title:      HOL/Decision_Procs/Parametric_Ferrante_Rackoff.thy
  Author: Amine Chaieb
*)

section ‹A formalization of Ferrante and Rackoff's procedure with polynomial parameters, see Paper in CALCULEMUS 2008›

theory Parametric_Ferrante_Rackoff
imports
  Reflected_Multivariate_Polynomial
  Dense_Linear_Order
  DP_Library
  "HOL-Library.Code_Target_Numeral"
begin

subsection ‹Terms›

datatype (plugins del: size) tm = CP poly | Bound nat | Add tm tm | Mul poly tm
  | Neg tm | Sub tm tm | CNP nat poly tm

instantiation tm :: size
begin

primrec size_tm :: "tm ==> nat"
  where
    "size_tm (CP c) = polysize c"
  | "size_tm (Bound n) = 1"
  | "size_tm (Neg a) = 1 + size_tm a"
  | "size_tm (Add a b) = 1 + size_tm a + size_tm b"
  | "size_tm (Sub a b) = 3 + size_tm a + size_tm b"
  | "size_tm (Mul c a) = 1 + polysize c + size_tm a"
  | "size_tm (CNP n c a) = 3 + polysize c + size_tm a "

instance ..

end

text ‹Semantics of terms tm.›
primrec Itm :: "'a::field_char_0 list ==> 'a list ==> tm ==> 'a"
  where
    "Itm vs bs (CP c) = (Ipoly vs c)"
  | "Itm vs bs (Bound n) = bs!n"
  | "Itm vs bs (Neg a) = -(Itm vs bs a)"
  | "Itm vs bs (Add a b) = Itm vs bs a + Itm vs bs b"
  | "Itm vs bs (Sub a b) = Itm vs bs a - Itm vs bs b"
  | "Itm vs bs (Mul c a) = (Ipoly vs c) * Itm vs bs a"
  | "Itm vs bs (CNP n c t) = (Ipoly vs c)*(bs!n) + Itm vs bs t"

fun allpolys :: "(poly ==> bool) ==> tm ==> bool"
  where
    "allpolys P (CP c) = P c"
  | "allpolys P (CNP n c p) = (P c ∧ allpolys P p)"
  | "allpolys P (Mul c p) = (P c ∧ allpolys P p)"
  | "allpolys P (Neg p) = allpolys P p"
  | "allpolys P (Add p q) = (allpolys P p ∧ allpolys P q)"
  | "allpolys P (Sub p q) = (allpolys P p ∧ allpolys P q)"
  | "allpolys P p = True"

primrec tmboundslt :: "nat ==> tm ==> bool"
  where
    "tmboundslt n (CP c) = True"
  | "tmboundslt n (Bound m) = (m < n)"
  | "tmboundslt n (CNP m c a) = (m < n ∧ tmboundslt n a)"
  | "tmboundslt n (Neg a) = tmboundslt n a"
  | "tmboundslt n (Add a b) = (tmboundslt n a ∧ tmboundslt n b)"
  | "tmboundslt n (Sub a b) = (tmboundslt n a ∧ tmboundslt n b)"
  | "tmboundslt n (Mul i a) = tmboundslt n a"

primrec tmbound0 :: "tm ==> bool"  🍋 ‹a ‹tm› is 🪙‹independent› of Bound 0›
  where
    "tmbound0 (CP c) = True"
  | "tmbound0 (Bound n) = (n>0)"
  | "tmbound0 (CNP n c a) = (n≠0 ∧ tmbound0 a)"
  | "tmbound0 (Neg a) = tmbound0 a"
  | "tmbound0 (Add a b) = (tmbound0 a ∧ tmbound0 b)"
  | "tmbound0 (Sub a b) = (tmbound0 a ∧ tmbound0 b)"
  | "tmbound0 (Mul i a) = tmbound0 a"

lemma tmbound0_I:
  assumes "tmbound0 a"
  shows "Itm vs (b#bs) a = Itm vs (b'#bs) a"
  using assms by (induct a rule: tm.induct) auto

primrec tmbound :: "nat ==> tm ==> bool"  🍋 ‹a ‹tm› is 🪙‹independent› of Bound n›
  where
    "tmbound n (CP c) = True"
  | "tmbound n (Bound m) = (n ≠ m)"
  | "tmbound n (CNP m c a) = (n≠m ∧ tmbound n a)"
  | "tmbound n (Neg a) = tmbound n a"
  | "tmbound n (Add a b) = (tmbound n a ∧ tmbound n b)"
  | "tmbound n (Sub a b) = (tmbound n a ∧ tmbound n b)"
  | "tmbound n (Mul i a) = tmbound n a"

lemma tmbound0_tmbound_iff: "tmbound 0 t = tmbound0 t"
  by (induct t) auto

lemma tmbound_I:
  assumes bnd: "tmboundslt (length bs) t"
    and nb: "tmbound n t"
    and le: "n ≤ length bs"
  shows "Itm vs (bs[n:=x]) t = Itm vs bs t"
  using nb le bnd
  by (induct t rule: tm.induct) auto

fun decrtm0 :: "tm ==> tm"
  where
    "decrtm0 (Bound n) = Bound (n - 1)"
  | "decrtm0 (Neg a) = Neg (decrtm0 a)"
  | "decrtm0 (Add a b) = Add (decrtm0 a) (decrtm0 b)"
  | "decrtm0 (Sub a b) = Sub (decrtm0 a) (decrtm0 b)"
  | "decrtm0 (Mul c a) = Mul c (decrtm0 a)"
  | "decrtm0 (CNP n c a) = CNP (n - 1) c (decrtm0 a)"
  | "decrtm0 a = a"

fun incrtm0 :: "tm ==> tm"
  where
    "incrtm0 (Bound n) = Bound (n + 1)"
  | "incrtm0 (Neg a) = Neg (incrtm0 a)"
  | "incrtm0 (Add a b) = Add (incrtm0 a) (incrtm0 b)"
  | "incrtm0 (Sub a b) = Sub (incrtm0 a) (incrtm0 b)"
  | "incrtm0 (Mul c a) = Mul c (incrtm0 a)"
  | "incrtm0 (CNP n c a) = CNP (n + 1) c (incrtm0 a)"
  | "incrtm0 a = a"

lemma decrtm0:
  assumes nb: "tmbound0 t"
  shows "Itm vs (x # bs) t = Itm vs bs (decrtm0 t)"
  using nb by (induct t rule: decrtm0.induct) simp_all

lemma incrtm0: "Itm vs (x#bs) (incrtm0 t) = Itm vs bs t"
  by (induct t rule: decrtm0.induct) simp_all

primrec decrtm :: "nat ==> tm ==> tm"
  where
    "decrtm m (CP c) = (CP c)"
  | "decrtm m (Bound n) = (if n < m then Bound n else Bound (n - 1))"
  | "decrtm m (Neg a) = Neg (decrtm m a)"
  | "decrtm m (Add a b) = Add (decrtm m a) (decrtm m b)"
  | "decrtm m (Sub a b) = Sub (decrtm m a) (decrtm m b)"
  | "decrtm m (Mul c a) = Mul c (decrtm m a)"
  | "decrtm m (CNP n c a) = (if n < m then CNP n c (decrtm m a) else CNP (n - 1) c (decrtm m a))"

primrec removen :: "nat ==> 'a list ==> 'a list"
  where
    "removen n [] = []"
  | "removen n (x#xs) = (if n=0 then xs else (x#(removen (n - 1) xs)))"

lemma removen_same: "n ≥ length xs ==> removen n xs = xs"
  by (induct xs arbitrary: n) auto

lemma nth_length_exceeds: "n ≥ length xs ==> xs!n = []!(n - length xs)"
  by (induct xs arbitrary: n) auto

lemma removen_length: "length (removen n xs) = (if n ≥ length xs then length xs else length xs - 1)"
  by (induct xs arbitrary: n) auto

lemma removen_nth:
  "(removen n xs)!m =
    (if n ≥ length xs then xs!m
     else if m < n then xs!m
     else if m ≤ length xs then xs!(Suc m)
     else []!(m - (length xs - 1)))"
proof (induct xs arbitrary: n m)
  case Nil
  then show ?case by simp
next
  case (Cons x xs)
  let ?l = "length (x # xs)"
  consider "n ≥ ?l" | "n < ?l" by arith
  then show ?case
  proof cases
    case 1
    with removen_same[OF this] show ?thesis by simp
  next
    case nl: 2
    consider "m < n" | "m ≥ n" by arith
    then show ?thesis
    proof cases
      case 1
      then show ?thesis
        using Cons by (cases m) auto
    next
      case 2
      consider "m ≤ ?l" | "m > ?l" by arith
      then show ?thesis
      proof cases
        case 1
        then show ?thesis
          using Cons by (cases m) auto
      next
        case ml: 2
        have th: "length (removen n (x # xs)) = length xs"
          using removen_length[where n = n and xs= "x # xs"] nl by simp
        with ml have "m ≥ length (removen n (x # xs))"
          by auto
        from th nth_length_exceeds[OF this] have "(removen n (x # xs))!m = [] ! (m - length xs)"
           by auto
        then have "(removen n (x # xs))!m = [] ! (m - (length (x # xs) - 1))"
          by auto
        then show ?thesis
          using ml nl by auto
      qed
    qed
  qed
qed

lemma decrtm:
  assumes bnd: "tmboundslt (length bs) t"
    and nb: "tmbound m t"
    and nle: "m ≤ length bs"
  shows "Itm vs (removen m bs) (decrtm m t) = Itm vs bs t"
  using bnd nb nle by (induct t rule: tm.induct) (auto simp: removen_nth)

primrec tmsubst0:: "tm ==> tm ==> tm"
  where
    "tmsubst0 t (CP c) = CP c"
  | "tmsubst0 t (Bound n) = (if n=0 then t else Bound n)"
  | "tmsubst0 t (CNP n c a) = (if n=0 then Add (Mul c t) (tmsubst0 t a) else CNP n c (tmsubst0 t a))"
  | "tmsubst0 t (Neg a) = Neg (tmsubst0 t a)"
  | "tmsubst0 t (Add a b) = Add (tmsubst0 t a) (tmsubst0 t b)"
  | "tmsubst0 t (Sub a b) = Sub (tmsubst0 t a) (tmsubst0 t b)"
  | "tmsubst0 t (Mul i a) = Mul i (tmsubst0 t a)"

lemma tmsubst0: "Itm vs (x # bs) (tmsubst0 t a) = Itm vs (Itm vs (x # bs) t # bs) a"
  by (induct a rule: tm.induct) auto

lemma tmsubst0_nb: "tmbound0 t ==> tmbound0 (tmsubst0 t a)"
  by (induct a rule: tm.induct) auto

primrec tmsubst:: "nat ==> tm ==> tm ==> tm"
  where
    "tmsubst n t (CP c) = CP c"
  | "tmsubst n t (Bound m) = (if n=m then t else Bound m)"
  | "tmsubst n t (CNP m c a) =
      (if n = m then Add (Mul c t) (tmsubst n t a) else CNP m c (tmsubst n t a))"
  | "tmsubst n t (Neg a) = Neg (tmsubst n t a)"
  | "tmsubst n t (Add a b) = Add (tmsubst n t a) (tmsubst n t b)"
  | "tmsubst n t (Sub a b) = Sub (tmsubst n t a) (tmsubst n t b)"
  | "tmsubst n t (Mul i a) = Mul i (tmsubst n t a)"

lemma tmsubst:
  assumes nb: "tmboundslt (length bs) a"
    and nlt: "n ≤ length bs"
  shows "Itm vs bs (tmsubst n t a) = Itm vs (bs[n:= Itm vs bs t]) a"
  using nb nlt
  by (induct a rule: tm.induct) auto

lemma tmsubst_nb0:
  assumes tnb: "tmbound0 t"
  shows "tmbound0 (tmsubst 0 t a)"
  using tnb
  by (induct a rule: tm.induct) auto

lemma tmsubst_nb:
  assumes tnb: "tmbound m t"
  shows "tmbound m (tmsubst m t a)"
  using tnb
  by (induct a rule: tm.induct) auto

lemma incrtm0_tmbound: "tmbound n t ==> tmbound (Suc n) (incrtm0 t)"
  by (induct t) auto


text ‹Simplification.›

fun tmadd:: "tm ==> tm ==> tm"
  where
    "tmadd (CNP n1 c1 r1) (CNP n2 c2 r2) =
      (if n1 = n2 then
        let c = c1 +🪙p c2
        in if c = 0🪙p then tmadd r1 r2 else CNP n1 c (tmadd r1 r2)
      else if n1 ≤ n2 then (CNP n1 c1 (tmadd r1 (CNP n2 c2 r2)))
      else (CNP n2 c2 (tmadd (CNP n1 c1 r1) r2)))"
  | "tmadd (CNP n1 c1 r1) t = CNP n1 c1 (tmadd r1 t)"
  | "tmadd t (CNP n2 c2 r2) = CNP n2 c2 (tmadd t r2)"
  | "tmadd (CP b1) (CP b2) = CP (b1 +🪙p b2)"
  | "tmadd a b = Add a b"

lemma tmadd [simp]: "Itm vs bs (tmadd t s) = Itm vs bs (Add t s)"
proof (induct t s rule: tmadd.induct)
  case (1 n1 c1 r1 n2 c2 r2)
  show ?case
  proof (cases "c1 +🪙p c2 = 0🪙p")
    case 0: True
    show ?thesis
    proof (cases "n1 ≤ n2")
      case True
      with 0 show ?thesis
        apply (simp add: 1)
        by (metis INum_int(2) Ipoly.simps(1) comm_semiring_class.distrib mult_eq_0_iff polyadd)
    qed (use 0 1 in auto)
  next
    case False
    then show ?thesis
      using 1 comm_semiring_class.distrib by auto
  qed
qed auto

lemma tmadd_nb0[simp]: "tmbound0 t ==> tmbound0 s ==> tmbound0 (tmadd t s)"
  by (induct t s rule: tmadd.induct) (auto simp: Let_def)

lemma tmadd_nb[simp]: "tmbound n t ==> tmbound n s ==> tmbound n (tmadd t s)"
  by (induct t s rule: tmadd.induct) (auto simp: Let_def)

lemma tmadd_blt[simp]: "tmboundslt n t ==> tmboundslt n s ==> tmboundslt n (tmadd t s)"
  by (induct t s rule: tmadd.induct) (auto simp: Let_def)

lemma tmadd_allpolys_npoly[simp]:
  "allpolys isnpoly t ==> allpolys isnpoly s ==> allpolys isnpoly (tmadd t s)"
  by (induct t s rule: tmadd.induct) (simp_all add: Let_def polyadd_norm)

fun tmmul:: "tm ==> poly ==> tm"
  where
    "tmmul (CP j) = (λi. CP (i *🪙p j))"
  | "tmmul (CNP n c a) = (λi. CNP n (i *🪙p c) (tmmul a i))"
  | "tmmul t = (λi. Mul i t)"

lemma tmmul[simp]: "Itm vs bs (tmmul t i) = Itm vs bs (Mul i t)"
  by (induct t arbitrary: i rule: tmmul.induct) (simp_all add: field_simps)

lemma tmmul_nb0[simp]: "tmbound0 t ==> tmbound0 (tmmul t i)"
  by (induct t arbitrary: i rule: tmmul.induct) auto

lemma tmmul_nb[simp]: "tmbound n t ==> tmbound n (tmmul t i)"
  by (induct t arbitrary: n rule: tmmul.induct) auto

lemma tmmul_blt[simp]: "tmboundslt n t ==> tmboundslt n (tmmul t i)"
  by (induct t arbitrary: i rule: tmmul.induct) (auto simp: Let_def)

lemma tmmul_allpolys_npoly[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "allpolys isnpoly t ==> isnpoly c ==> allpolys isnpoly (tmmul t c)"
  by (induct t rule: tmmul.induct) (simp_all add: Let_def polymul_norm)

definition tmneg :: "tm ==> tm"
  where "tmneg t ≡ tmmul t (C (- 1,1))"

definition tmsub :: "tm ==> tm ==> tm"
  where "tmsub s t ≡ (if s = t then CP 0🪙p else tmadd s (tmneg t))"

lemma tmneg[simp]: "Itm vs bs (tmneg t) = Itm vs bs (Neg t)"
  using tmneg_def[of t] by simp

lemma tmneg_nb0[simp]: "tmbound0 t ==> tmbound0 (tmneg t)"
  using tmneg_def by simp

lemma tmneg_nb[simp]: "tmbound n t ==> tmbound n (tmneg t)"
  using tmneg_def by simp

lemma tmneg_blt[simp]: "tmboundslt n t ==> tmboundslt n (tmneg t)"
  using tmneg_def by simp

lemma [simp]: "isnpoly (C (-1, 1))"
  by (simp add: isnpoly_def)

lemma tmneg_allpolys_npoly[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "allpolys isnpoly t ==> allpolys isnpoly (tmneg t)"
  by (auto simp: tmneg_def)

lemma tmsub[simp]: "Itm vs bs (tmsub a b) = Itm vs bs (Sub a b)"
  using tmsub_def by simp

lemma tmsub_nb0[simp]: "tmbound0 t ==> tmbound0 s ==> tmbound0 (tmsub t s)"
  using tmsub_def by simp

lemma tmsub_nb[simp]: "tmbound n t ==> tmbound n s ==> tmbound n (tmsub t s)"
  using tmsub_def by simp

lemma tmsub_blt[simp]: "tmboundslt n t ==> tmboundslt n s ==> tmboundslt n (tmsub t s)"
  using tmsub_def by simp

lemma tmsub_allpolys_npoly[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "allpolys isnpoly t ==> allpolys isnpoly s ==> allpolys isnpoly (tmsub t s)"
  by (simp add: tmsub_def isnpoly_def)

fun simptm :: "tm ==> tm"
  where
    "simptm (CP j) = CP (polynate j)"
  | "simptm (Bound n) = CNP n (1)🪙p (CP 0🪙p)"
  | "simptm (Neg t) = tmneg (simptm t)"
  | "simptm (Add t s) = tmadd (simptm t) (simptm s)"
  | "simptm (Sub t s) = tmsub (simptm t) (simptm s)"
  | "simptm (Mul i t) =
      (let i' = polynate i in if i' = 0🪙p then CP 0🪙p else tmmul (simptm t) i')"
  | "simptm (CNP n c t) =
      (let c' = polynate c in if c' = 0🪙p then simptm t else tmadd (CNP n c' (CP 0🪙p)) (simptm t))"

lemma polynate_stupid:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "polynate t = 0🪙p ==> Ipoly bs t = (0::'a)"
  by (metis INum_int(2) Ipoly.simps(1) polynate)

lemma simptm_ci[simp]: "Itm vs bs (simptm t) = Itm vs bs t"
  by (induct t rule: simptm.induct) (auto simp: Let_def polynate_stupid)

lemma simptm_tmbound0[simp]: "tmbound0 t ==> tmbound0 (simptm t)"
  by (induct t rule: simptm.induct) (auto simp: Let_def)

lemma simptm_nb[simp]: "tmbound n t ==> tmbound n (simptm t)"
  by (induct t rule: simptm.induct) (auto simp: Let_def)

lemma simptm_nlt[simp]: "tmboundslt n t ==> tmboundslt n (simptm t)"
  by (induct t rule: simptm.induct) (auto simp: Let_def)

lemma [simp]: "isnpoly 0🪙p"
  and [simp]: "isnpoly (C (1, 1))"
  by (simp_all add: isnpoly_def)

lemma simptm_allpolys_npoly[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "allpolys isnpoly (simptm p)"
  by (induct p rule: simptm.induct) (auto simp: Let_def)

declare let_cong[fundef_cong del]

fun split0 :: "tm ==> poly × tm"
  where
    "split0 (Bound 0) = ((1)🪙p, CP 0🪙p)"
  | "split0 (CNP 0 c t) = (let (c', t') = split0 t in (c +🪙p c', t'))"
  | "split0 (Neg t) = (let (c, t') = split0 t in (~🪙p c, Neg t'))"
  | "split0 (CNP n c t) = (let (c', t') = split0 t in (c', CNP n c t'))"
  | "split0 (Add s t) = (let (c1, s') = split0 s; (c2, t') = split0 t in (c1 +🪙p c2, Add s' t'))"
  | "split0 (Sub s t) = (let (c1, s') = split0 s; (c2, t') = split0 t in (c1 -🪙p c2, Sub s' t'))"
  | "split0 (Mul c t) = (let (c', t') = split0 t in (c *🪙p c', Mul c t'))"
  | "split0 t = (0🪙p, t)"

declare let_cong[fundef_cong]

lemma split0_stupid[simp]: "∃x y. (x, y) = split0 p"
  using prod.collapse by blast

lemma split0:
  "tmbound 0 (snd (split0 t)) ∧ Itm vs bs (CNP 0 (fst (split0 t)) (snd (split0 t))) = Itm vs bs t"
proof (induct t rule: split0.induct)
  case (7 c t)
  then show ?case
    by (simp add: Let_def split_def mult.assoc flip: distrib_left)
qed (auto simp: Let_def split_def field_simps)

lemma split0_ci: "split0 t = (c',t') ==> Itm vs bs t = Itm vs bs (CNP 0 c' t')"
proof -
  fix c' t'
  assume "split0 t = (c', t')"
  then have "c' = fst (split0 t)" "t' = snd (split0 t)"
    by auto
  with split0[where t="t" and bs="bs"] show "Itm vs bs t = Itm vs bs (CNP 0 c' t')"
    by simp
qed

lemma split0_nb0:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "split0 t = (c',t') ==> tmbound 0 t'"
proof -
  fix c' t'
  assume "split0 t = (c', t')"
  then have "c' = fst (split0 t)" "t' = snd (split0 t)"
    by auto
  with conjunct1[OF split0[where t="t"]] show "tmbound 0 t'"
    by simp
qed

lemma split0_nb0'[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "tmbound0 (snd (split0 t))"
  using split0_nb0[of t "fst (split0 t)" "snd (split0 t)"]
  by (simp add: tmbound0_tmbound_iff)

lemma split0_nb:
  assumes nb: "tmbound n t"
  shows "tmbound n (snd (split0 t))"
  using nb by (induct t rule: split0.induct) (auto simp: Let_def split_def)

lemma split0_blt:
  assumes nb: "tmboundslt n t"
  shows "tmboundslt n (snd (split0 t))"
  using nb by (induct t rule: split0.induct) (auto simp: Let_def split_def)

lemma tmbound_split0: "tmbound 0 t ==> Ipoly vs (fst (split0 t)) = 0"
  by (induct t rule: split0.induct) (auto simp: Let_def split_def)

lemma tmboundslt_split0: "tmboundslt n t ==> Ipoly vs (fst (split0 t)) = 0 ∨ n > 0"
  by (induct t rule: split0.induct) (auto simp: Let_def split_def)

lemma tmboundslt0_split0: "tmboundslt 0 t ==> Ipoly vs (fst (split0 t)) = 0"
  by (induct t rule: split0.induct) (auto simp: Let_def split_def)

lemma allpolys_split0: "allpolys isnpoly p ==> allpolys isnpoly (snd (split0 p))"
  by (induct p rule: split0.induct) (auto simp  add: isnpoly_def Let_def split_def)

lemma isnpoly_fst_split0:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "allpolys isnpoly p ==> isnpoly (fst (split0 p))"
  by (induct p rule: split0.induct)
    (auto simp  add: polyadd_norm polysub_norm polyneg_norm polymul_norm Let_def split_def)


subsection ‹Formulae›

datatype (plugins del: size) fm = T | F | Le tm | Lt tm | Eq tm | NEq tm |
  Not fm | And fm fm | Or fm fm | Imp fm fm | Iff fm fm | E fm | A fm

instantiation fm :: size
begin

primrec size_fm :: "fm ==> nat"
  where
    "size_fm (Not p) = 1 + size_fm p"
  | "size_fm (And p q) = 1 + size_fm p + size_fm q"
  | "size_fm (Or p q) = 1 + size_fm p + size_fm q"
  | "size_fm (Imp p q) = 3 + size_fm p + size_fm q"
  | "size_fm (Iff p q) = 3 + 2 * (size_fm p + size_fm q)"
  | "size_fm (E p) = 1 + size_fm p"
  | "size_fm (A p) = 4 + size_fm p"
  | "size_fm T = 1"
  | "size_fm F = 1"
  | "size_fm (Le _) = 1"
  | "size_fm (Lt _) = 1"
  | "size_fm (Eq _) = 1"
  | "size_fm (NEq _) = 1"

instance ..

end

lemma fmsize_pos [simp]: "size p > 0" for p :: fm
  by (induct p) simp_all

text ‹Semantics of formulae (fm).›
primrec Ifm ::"'a::linordered_field list ==> 'a list ==> fm ==> bool"
  where
    "Ifm vs bs T = True"
  | "Ifm vs bs F = False"
  | "Ifm vs bs (Lt a) = (Itm vs bs a < 0)"
  | "Ifm vs bs (Le a) = (Itm vs bs a ≤ 0)"
  | "Ifm vs bs (Eq a) = (Itm vs bs a = 0)"
  | "Ifm vs bs (NEq a) = (Itm vs bs a ≠ 0)"
  | "Ifm vs bs (Not p) = (¬ (Ifm vs bs p))"
  | "Ifm vs bs (And p q) = (Ifm vs bs p ∧ Ifm vs bs q)"
  | "Ifm vs bs (Or p q) = (Ifm vs bs p ∨ Ifm vs bs q)"
  | "Ifm vs bs (Imp p q) = ((Ifm vs bs p) ⟶ (Ifm vs bs q))"
  | "Ifm vs bs (Iff p q) = (Ifm vs bs p = Ifm vs bs q)"
  | "Ifm vs bs (E p) = (∃x. Ifm vs (x#bs) p)"
  | "Ifm vs bs (A p) = (∀x. Ifm vs (x#bs) p)"

fun not:: "fm ==> fm"
  where
    "not (Not (Not p)) = not p"
  | "not (Not p) = p"
  | "not T = F"
  | "not F = T"
  | "not (Lt t) = Le (tmneg t)"
  | "not (Le t) = Lt (tmneg t)"
  | "not (Eq t) = NEq t"
  | "not (NEq t) = Eq t"
  | "not p = Not p"

lemma not[simp]: "Ifm vs bs (not p) = Ifm vs bs (Not p)"
  by (induct p rule: not.induct) auto

definition conj :: "fm ==> fm ==> fm"
  where "conj p q ≡
    (if p = F ∨ q = F then F
     else if p = T then q
     else if q = T then p
     else if p = q then p
     else And p q)"

lemma conj[simp]: "Ifm vs bs (conj p q) = Ifm vs bs (And p q)"
  by (cases "p=F ∨ q=F", simp_all add: conj_def) (cases p, simp_all)

definition disj :: "fm ==> fm ==> fm"
  where "disj p q ≡
    (if (p = T ∨ q = T) then T
     else if p = F then q
     else if q = F then p
     else if p = q then p
     else Or p q)"

lemma disj[simp]: "Ifm vs bs (disj p q) = Ifm vs bs (Or p q)"
  by (cases "p = T ∨ q = T", simp_all add: disj_def) (cases p, simp_all)

definition imp :: "fm ==> fm ==> fm"
  where "imp p q ≡
    (if p = F ∨ q = T ∨ p = q then T
     else if p = T then q
     else if q = F then not p
     else Imp p q)"

lemma imp[simp]: "Ifm vs bs (imp p q) = Ifm vs bs (Imp p q)"
  by (cases "p = F ∨ q = T") (simp_all add: imp_def)

definition iff :: "fm ==> fm ==> fm"
  where "iff p q ≡
   (if p = q then T
    else if p = Not q ∨ Not p = q then F
    else if p = F then not q
    else if q = F then not p
    else if p = T then q
    else if q = T then p
    else Iff p q)"

lemma iff[simp]: "Ifm vs bs (iff p q) = Ifm vs bs (Iff p q)"
  by (unfold iff_def, cases "p = q", simp, cases "p = Not q", simp) (cases "Not p= q", auto)

text ‹Quantifier freeness.›
fun qfree:: "fm ==> bool"
  where
    "qfree (E p) = False"
  | "qfree (A p) = False"
  | "qfree (Not p) = qfree p"
  | "qfree (And p q) = (qfree p ∧ qfree q)"
  | "qfree (Or p q) = (qfree p ∧ qfree q)"
  | "qfree (Imp p q) = (qfree p ∧ qfree q)"
  | "qfree (Iff p q) = (qfree p ∧ qfree q)"
  | "qfree p = True"

text ‹Boundedness and substitution.›
primrec boundslt :: "nat ==> fm ==> bool"
  where
    "boundslt n T = True"
  | "boundslt n F = True"
  | "boundslt n (Lt t) = tmboundslt n t"
  | "boundslt n (Le t) = tmboundslt n t"
  | "boundslt n (Eq t) = tmboundslt n t"
  | "boundslt n (NEq t) = tmboundslt n t"
  | "boundslt n (Not p) = boundslt n p"
  | "boundslt n (And p q) = (boundslt n p ∧ boundslt n q)"
  | "boundslt n (Or p q) = (boundslt n p ∧ boundslt n q)"
  | "boundslt n (Imp p q) = ((boundslt n p) ∧ (boundslt n q))"
  | "boundslt n (Iff p q) = (boundslt n p ∧ boundslt n q)"
  | "boundslt n (E p) = boundslt (Suc n) p"
  | "boundslt n (A p) = boundslt (Suc n) p"

fun bound0:: "fm ==> bool"  🍋 ‹a formula is independent of Bound 0›
  where
    "bound0 T = True"
  | "bound0 F = True"
  | "bound0 (Lt a) = tmbound0 a"
  | "bound0 (Le a) = tmbound0 a"
  | "bound0 (Eq a) = tmbound0 a"
  | "bound0 (NEq a) = tmbound0 a"
  | "bound0 (Not p) = bound0 p"
  | "bound0 (And p q) = (bound0 p ∧ bound0 q)"
  | "bound0 (Or p q) = (bound0 p ∧ bound0 q)"
  | "bound0 (Imp p q) = ((bound0 p) ∧ (bound0 q))"
  | "bound0 (Iff p q) = (bound0 p ∧ bound0 q)"
  | "bound0 p = False"

lemma bound0_I:
  assumes bp: "bound0 p"
  shows "Ifm vs (b#bs) p = Ifm vs (b'#bs) p"
  using bp tmbound0_I[where b="b" and bs="bs" and b'="b'"]
  by (induct p rule: bound0.induct) auto

primrec bound:: "nat ==> fm ==> bool"  🍋 ‹a formula is independent of Bound n›
  where
    "bound m T = True"
  | "bound m F = True"
  | "bound m (Lt t) = tmbound m t"
  | "bound m (Le t) = tmbound m t"
  | "bound m (Eq t) = tmbound m t"
  | "bound m (NEq t) = tmbound m t"
  | "bound m (Not p) = bound m p"
  | "bound m (And p q) = (bound m p ∧ bound m q)"
  | "bound m (Or p q) = (bound m p ∧ bound m q)"
  | "bound m (Imp p q) = ((bound m p) ∧ (bound m q))"
  | "bound m (Iff p q) = (bound m p ∧ bound m q)"
  | "bound m (E p) = bound (Suc m) p"
  | "bound m (A p) = bound (Suc m) p"

lemma bound_I:
  assumes bnd: "boundslt (length bs) p"
    and nb: "bound n p"
    and le: "n ≤ length bs"
  shows "Ifm vs (bs[n:=x]) p = Ifm vs bs p"
  using bnd nb le tmbound_I[where bs=bs and vs = vs]
proof (induct p arbitrary: bs n rule: fm.induct)
  case (E p bs n)
  have "Ifm vs ((y#bs)[Suc n:=x]) p = Ifm vs (y#bs) p" for y
  proof -
    from E have bnd: "boundslt (length (y#bs)) p"
      and nb: "bound (Suc n) p" and le: "Suc n ≤ length (y#bs)" by simp+
    from E.hyps[OF bnd nb le tmbound_I] show ?thesis .
  qed
  then show ?case by simp
next
  case (A p bs n)
  have "Ifm vs ((y#bs)[Suc n:=x]) p = Ifm vs (y#bs) p" for y
  proof -
    from A have bnd: "boundslt (length (y#bs)) p"
      and nb: "bound (Suc n) p"
      and le: "Suc n ≤ length (y#bs)"
      by simp_all
    from A.hyps[OF bnd nb le tmbound_I] show ?thesis .
  qed
  then show ?case by simp
qed auto

fun decr0 :: "fm ==> fm"
  where
    "decr0 (Lt a) = Lt (decrtm0 a)"
  | "decr0 (Le a) = Le (decrtm0 a)"
  | "decr0 (Eq a) = Eq (decrtm0 a)"
  | "decr0 (NEq a) = NEq (decrtm0 a)"
  | "decr0 (Not p) = Not (decr0 p)"
  | "decr0 (And p q) = conj (decr0 p) (decr0 q)"
  | "decr0 (Or p q) = disj (decr0 p) (decr0 q)"
  | "decr0 (Imp p q) = imp (decr0 p) (decr0 q)"
  | "decr0 (Iff p q) = iff (decr0 p) (decr0 q)"
  | "decr0 p = p"

lemma decr0:
  assumes "bound0 p"
  shows "Ifm vs (x#bs) p = Ifm vs bs (decr0 p)"
  using assms by (induct p rule: decr0.induct) (simp_all add: decrtm0)

primrec decr :: "nat ==> fm ==> fm"
  where
    "decr m T = T"
  | "decr m F = F"
  | "decr m (Lt t) = (Lt (decrtm m t))"
  | "decr m (Le t) = (Le (decrtm m t))"
  | "decr m (Eq t) = (Eq (decrtm m t))"
  | "decr m (NEq t) = (NEq (decrtm m t))"
  | "decr m (Not p) = Not (decr m p)"
  | "decr m (And p q) = conj (decr m p) (decr m q)"
  | "decr m (Or p q) = disj (decr m p) (decr m q)"
  | "decr m (Imp p q) = imp (decr m p) (decr m q)"
  | "decr m (Iff p q) = iff (decr m p) (decr m q)"
  | "decr m (E p) = E (decr (Suc m) p)"
  | "decr m (A p) = A (decr (Suc m) p)"

lemma decr:
  assumes bnd: "boundslt (length bs) p"
    and nb: "bound m p"
    and nle: "m < length bs"
  shows "Ifm vs (removen m bs) (decr m p) = Ifm vs bs p"
  using bnd nb nle
proof (induct p arbitrary: bs m rule: fm.induct)
  case (E p bs m)
  have "Ifm vs (removen (Suc m) (x#bs)) (decr (Suc m) p) = Ifm vs (x#bs) p" for x
  proof -
    from E
    have bnd: "boundslt (length (x#bs)) p"
      and nb: "bound (Suc m) p"
      and nle: "Suc m < length (x#bs)"
      by auto
    from E(1)[OF bnd nb nle] show ?thesis .
  qed
  then show ?case by auto
next
  case (A p bs m)
  have "Ifm vs (removen (Suc m) (x#bs)) (decr (Suc m) p) = Ifm vs (x#bs) p" for x
  proof -
    from A
    have bnd: "boundslt (length (x#bs)) p"
      and nb: "bound (Suc m) p"
      and nle: "Suc m < length (x#bs)"
      by auto
    from A(1)[OF bnd nb nle] show ?thesis .
  qed
  then show ?case by auto
qed (auto simp: decrtm removen_nth)

primrec subst0 :: "tm ==> fm ==> fm"
  where
    "subst0 t T = T"
  | "subst0 t F = F"
  | "subst0 t (Lt a) = Lt (tmsubst0 t a)"
  | "subst0 t (Le a) = Le (tmsubst0 t a)"
  | "subst0 t (Eq a) = Eq (tmsubst0 t a)"
  | "subst0 t (NEq a) = NEq (tmsubst0 t a)"
  | "subst0 t (Not p) = Not (subst0 t p)"
  | "subst0 t (And p q) = And (subst0 t p) (subst0 t q)"
  | "subst0 t (Or p q) = Or (subst0 t p) (subst0 t q)"
  | "subst0 t (Imp p q) = Imp (subst0 t p) (subst0 t q)"
  | "subst0 t (Iff p q) = Iff (subst0 t p) (subst0 t q)"
  | "subst0 t (E p) = E p"
  | "subst0 t (A p) = A p"

lemma subst0:
  assumes qf: "qfree p"
  shows "Ifm vs (x # bs) (subst0 t p) = Ifm vs ((Itm vs (x # bs) t) # bs) p"
  using qf tmsubst0[where x="x" and bs="bs" and t="t"]
  by (induct p rule: fm.induct) auto

lemma subst0_nb:
  assumes bp: "tmbound0 t"
    and qf: "qfree p"
  shows "bound0 (subst0 t p)"
  using qf tmsubst0_nb[OF bp] bp by (induct p rule: fm.induct) auto

primrec subst:: "nat ==> tm ==> fm ==> fm"
  where
    "subst n t T = T"
  | "subst n t F = F"
  | "subst n t (Lt a) = Lt (tmsubst n t a)"
  | "subst n t (Le a) = Le (tmsubst n t a)"
  | "subst n t (Eq a) = Eq (tmsubst n t a)"
  | "subst n t (NEq a) = NEq (tmsubst n t a)"
  | "subst n t (Not p) = Not (subst n t p)"
  | "subst n t (And p q) = And (subst n t p) (subst n t q)"
  | "subst n t (Or p q) = Or (subst n t p) (subst n t q)"
  | "subst n t (Imp p q) = Imp (subst n t p) (subst n t q)"
  | "subst n t (Iff p q) = Iff (subst n t p) (subst n t q)"
  | "subst n t (E p) = E (subst (Suc n) (incrtm0 t) p)"
  | "subst n t (A p) = A (subst (Suc n) (incrtm0 t) p)"

lemma subst:
  assumes nb: "boundslt (length bs) p"
    and nlm: "n ≤ length bs"
  shows "Ifm vs bs (subst n t p) = Ifm vs (bs[n:= Itm vs bs t]) p"
  using nb nlm
proof (induct p arbitrary: bs n t rule: fm.induct)
  case (E p bs n)
  have "Ifm vs (x#bs) (subst (Suc n) (incrtm0 t) p) =
        Ifm vs (x#bs[n:= Itm vs bs t]) p" for x
  proof -
    from E have bn: "boundslt (length (x#bs)) p"
      by simp
    from E have nlm: "Suc n ≤ length (x#bs)"
      by simp
    from E(1)[OF bn nlm]
    have "Ifm vs (x#bs) (subst (Suc n) (incrtm0 t) p) =
        Ifm vs ((x#bs)[Suc n:= Itm vs (x#bs) (incrtm0 t)]) p"
      by simp
    then show ?thesis
      by (simp add: incrtm0[where x="x" and bs="bs" and t="t"])
  qed
  then show ?case by simp
next
  case (A p bs n)
  have "Ifm vs (x#bs) (subst (Suc n) (incrtm0 t) p) =
        Ifm vs (x#bs[n:= Itm vs bs t]) p" for x
  proof -
    from A have bn: "boundslt (length (x#bs)) p"
      by simp
    from A have nlm: "Suc n ≤ length (x#bs)"
      by simp
    from A(1)[OF bn nlm]
    have "Ifm vs (x#bs) (subst (Suc n) (incrtm0 t) p) =
        Ifm vs ((x#bs)[Suc n:= Itm vs (x#bs) (incrtm0 t)]) p"
      by simp
    then show ?thesis
      by (simp add: incrtm0[where x="x" and bs="bs" and t="t"])
  qed
  then show ?case by simp
qed (auto simp: tmsubst)

lemma subst_nb:
  assumes "tmbound m t"
  shows "bound m (subst m t p)"
  using assms tmsubst_nb incrtm0_tmbound by (induct p arbitrary: m t rule: fm.induct) auto

lemma not_qf[simp]: "qfree p ==> qfree (not p)"
  by (induct p rule: not.induct) auto
lemma not_bn0[simp]: "bound0 p ==> bound0 (not p)"
  by (induct p rule: not.induct) auto
lemma not_nb[simp]: "bound n p ==> bound n (not p)"
  by (induct p rule: not.induct) auto
lemma not_blt[simp]: "boundslt n p ==> boundslt n (not p)"
  by (induct p rule: not.induct) auto

lemma conj_qf[simp]: "qfree p ==> qfree q ==> qfree (conj p q)"
  using conj_def by auto
lemma conj_nb0[simp]: "bound0 p ==> bound0 q ==> bound0 (conj p q)"
  using conj_def by auto
lemma conj_nb[simp]: "bound n p ==> bound n q ==> bound n (conj p q)"
  using conj_def by auto
lemma conj_blt[simp]: "boundslt n p ==> boundslt n q ==> boundslt n (conj p q)"
  using conj_def by auto

lemma disj_qf[simp]: "qfree p ==> qfree q ==> qfree (disj p q)"
  using disj_def by auto
lemma disj_nb0[simp]: "bound0 p ==> bound0 q ==> bound0 (disj p q)"
  using disj_def by auto
lemma disj_nb[simp]: "bound n p ==> bound n q ==> bound n (disj p q)"
  using disj_def by auto
lemma disj_blt[simp]: "boundslt n p ==> boundslt n q ==> boundslt n (disj p q)"
  using disj_def by auto

lemma imp_qf[simp]: "qfree p ==> qfree q ==> qfree (imp p q)"
  using imp_def by (cases "p = F ∨ q = T") (simp_all add: imp_def)
lemma imp_nb0[simp]: "bound0 p ==> bound0 q ==> bound0 (imp p q)"
  using imp_def by (cases "p = F ∨ q = T ∨ p = q") (simp_all add: imp_def)
lemma imp_nb[simp]: "bound n p ==> bound n q ==> bound n (imp p q)"
  using imp_def by (cases "p = F ∨ q = T ∨ p = q") (simp_all add: imp_def)
lemma imp_blt[simp]: "boundslt n p ==> boundslt n q ==> boundslt n (imp p q)"
  using imp_def by auto

lemma iff_qf[simp]: "qfree p ==> qfree q ==> qfree (iff p q)"
  unfolding iff_def by (cases "p = q") auto
lemma iff_nb0[simp]: "bound0 p ==> bound0 q ==> bound0 (iff p q)"
  using iff_def unfolding iff_def by (cases "p = q") auto
lemma iff_nb[simp]: "bound n p ==> bound n q ==> bound n (iff p q)"
  using iff_def unfolding iff_def by (cases "p = q") auto
lemma iff_blt[simp]: "boundslt n p ==> boundslt n q ==> boundslt n (iff p q)"
  using iff_def by auto
lemma decr0_qf: "bound0 p ==> qfree (decr0 p)"
  by (induct p) simp_all

fun isatom :: "fm ==> bool"  🍋 ‹test for atomicity›
  where
    "isatom T = True"
  | "isatom F = True"
  | "isatom (Lt a) = True"
  | "isatom (Le a) = True"
  | "isatom (Eq a) = True"
  | "isatom (NEq a) = True"
  | "isatom p = False"

lemma bound0_qf: "bound0 p ==> qfree p"
  by (induct p) simp_all

definition djf :: "('a ==> fm) ==> 'a ==> fm ==> fm"
  where "djf f p q ≡
    (if q = T then T
     else if q = F then f p
     else (let fp = f p in case fp of T ==> T | F ==> q | _ ==> Or (f p) q))"

definition evaldjf :: "('a ==> fm) ==> 'a list ==> fm"
  where "evaldjf f ps ≡ foldr (djf f) ps F"

lemma djf_Or: "Ifm vs bs (djf f p q) = Ifm vs bs (Or (f p) q)"
  by (cases "f p") (simp_all add: Let_def djf_def)

lemma evaldjf_ex: "Ifm vs bs (evaldjf f ps) ⟷ (∃p ∈ set ps. Ifm vs bs (f p))"
  by (induct ps) (simp_all add: evaldjf_def djf_Or)

lemma evaldjf_bound0:
  assumes "∀x ∈ set xs. bound0 (f x)"
  shows "bound0 (evaldjf f xs)"
  using assms
proof (induct xs)
  case Nil
  then show ?case
    by (simp add: evaldjf_def)
next
  case (Cons a xs)
  then show ?case
    by (cases "f a") (simp_all add: evaldjf_def djf_def Let_def)
qed

lemma evaldjf_qf:
  assumes "∀x∈ set xs. qfree (f x)"
  shows "qfree (evaldjf f xs)"
  using assms
proof (induct xs)
  case Nil
  then show ?case
    by (simp add: evaldjf_def)
next
  case (Cons a xs)
  then show ?case
    by (cases "f a") (simp_all add: evaldjf_def djf_def Let_def)
qed

fun disjuncts :: "fm ==> fm list"
  where
    "disjuncts (Or p q) = disjuncts p @ disjuncts q"
  | "disjuncts F = []"
  | "disjuncts p = [p]"

lemma disjuncts: "(∃q ∈ set (disjuncts p). Ifm vs bs q) = Ifm vs bs p"
  by (induct p rule: disjuncts.induct) auto

lemma disjuncts_nb:
  assumes "bound0 p"
  shows "∀q ∈ set (disjuncts p). bound0 q"
proof -
  from assms have "list_all bound0 (disjuncts p)"
    by (induct p rule: disjuncts.induct) auto
  then show ?thesis
    by (simp only: list_all_iff)
qed

lemma disjuncts_qf:
  assumes "qfree p"
  shows "∀q ∈ set (disjuncts p). qfree q"
proof -
  from assms have "list_all qfree (disjuncts p)"
    by (induct p rule: disjuncts.induct) auto
  then show ?thesis
    by (simp only: list_all_iff)
qed

definition DJ :: "(fm ==> fm) ==> fm ==> fm"
  where "DJ f p ≡ evaldjf f (disjuncts p)"

lemma DJ:
  assumes fdj: "∀p q. Ifm vs bs (f (Or p q)) = Ifm vs bs (Or (f p) (f q))"
    and fF: "f F = F"
  shows "Ifm vs bs (DJ f p) = Ifm vs bs (f p)"
proof -
  have "Ifm vs bs (DJ f p) = (∃q ∈ set (disjuncts p). Ifm vs bs (f q))"
    by (simp add: DJ_def evaldjf_ex)
  also have "… = Ifm vs bs (f p)"
    using fdj fF by (induct p rule: disjuncts.induct) auto
  finally show ?thesis .
qed

lemma DJ_qf:
  assumes fqf: "∀p. qfree p ⟶ qfree (f p)"
  shows "∀p. qfree p ⟶ qfree (DJ f p)"
proof clarify
  fix  p
  assume qf: "qfree p"
  have th: "DJ f p = evaldjf f (disjuncts p)"
    by (simp add: DJ_def)
  from disjuncts_qf[OF qf] have "∀q∈ set (disjuncts p). qfree q" .
  with fqf have th':"∀q∈ set (disjuncts p). qfree (f q)"
    by blast
  from evaldjf_qf[OF th'] th show "qfree (DJ f p)"
    by simp
qed

lemma DJ_qe:
  assumes qe: "∀bs p. qfree p ⟶ qfree (qe p) ∧ (Ifm vs bs (qe p) = Ifm vs bs (E p))"
  shows "∀bs p. qfree p ⟶ qfree (DJ qe p) ∧ (Ifm vs bs ((DJ qe p)) = Ifm vs bs (E p))"
proof clarify
  fix p :: fm and bs
  assume qf: "qfree p"
  from qe have qth: "∀p. qfree p ⟶ qfree (qe p)"
    by blast
  from DJ_qf[OF qth] qf have qfth:"qfree (DJ qe p)"
    by auto
  have "Ifm vs bs (DJ qe p) ⟷ (∃q∈ set (disjuncts p). Ifm vs bs (qe q))"
    by (simp add: DJ_def evaldjf_ex)
  also have "… = (∃q ∈ set(disjuncts p). Ifm vs bs (E q))"
    using qe disjuncts_qf[OF qf] by auto
  also have "… = Ifm vs bs (E p)"
    by (induct p rule: disjuncts.induct) auto
  finally show "qfree (DJ qe p) ∧ Ifm vs bs (DJ qe p) = Ifm vs bs (E p)"
    using qfth by blast
qed

fun conjuncts :: "fm ==> fm list"
  where
    "conjuncts (And p q) = conjuncts p @ conjuncts q"
  | "conjuncts T = []"
  | "conjuncts p = [p]"

definition list_conj :: "fm list ==> fm"
  where "list_conj ps ≡ foldr conj ps T"

definition CJNB :: "(fm ==> fm) ==> fm ==> fm"
  where "CJNB f p ≡
    (let cjs = conjuncts p;
      (yes, no) = partition bound0 cjs
     in conj (decr0 (list_conj yes)) (f (list_conj no)))"

lemma conjuncts_qf: "qfree p ==> ∀q ∈ set (conjuncts p). qfree q"
proof -
  assume qf: "qfree p"
  then have "list_all qfree (conjuncts p)"
    by (induct p rule: conjuncts.induct) auto
  then show ?thesis
    by (simp only: list_all_iff)
qed

lemma conjuncts: "(∀q∈ set (conjuncts p). Ifm vs bs q) = Ifm vs bs p"
  by (induct p rule: conjuncts.induct) auto

lemma conjuncts_nb:
  assumes "bound0 p"
  shows "∀q ∈ set (conjuncts p). bound0 q"
proof -
  from assms have "list_all bound0 (conjuncts p)"
    by (induct p rule:conjuncts.induct) auto
  then show ?thesis
    by (simp only: list_all_iff)
qed

fun islin :: "fm ==> bool"
  where
    "islin (And p q) = (islin p ∧ islin q ∧ p ≠ T ∧ p ≠ F ∧ q ≠ T ∧ q ≠ F)"
  | "islin (Or p q) = (islin p ∧ islin q ∧ p ≠ T ∧ p ≠ F ∧ q ≠ T ∧ q ≠ F)"
  | "islin (Eq (CNP 0 c s)) = (isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s)"
  | "islin (NEq (CNP 0 c s)) = (isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s)"
  | "islin (Lt (CNP 0 c s)) = (isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s)"
  | "islin (Le (CNP 0 c s)) = (isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s)"
  | "islin (Not p) = False"
  | "islin (Imp p q) = False"
  | "islin (Iff p q) = False"
  | "islin p = bound0 p"

lemma islin_stupid:
  assumes nb: "tmbound0 p"
  shows "islin (Lt p)"
    and "islin (Le p)"
    and "islin (Eq p)"
    and "islin (NEq p)"
  using nb by (cases p, auto, rename_tac nat a b, case_tac nat, auto)+

definition "lt p = (case p of CP (C c) ==> if 0>🪙N c then T else F| _ ==> Lt p)"
definition "le p = (case p of CP (C c) ==> if 0≥🪙N c then T else F | _ ==> Le p)"
definition "eq p = (case p of CP (C c) ==> if c = 0🪙N then T else F | _ ==> Eq p)"
definition "neq p = not (eq p)"

lemma lt: "allpolys isnpoly p ==> Ifm vs bs (lt p) = Ifm vs bs (Lt p)"
  by (auto simp: lt_def isnpoly_def split: tm.split poly.split)

lemma le: "allpolys isnpoly p ==> Ifm vs bs (le p) = Ifm vs bs (Le p)"
  by (auto simp: le_def isnpoly_def split: tm.split poly.split)

lemma eq: "allpolys isnpoly p ==> Ifm vs bs (eq p) = Ifm vs bs (Eq p)"
  by (auto simp: eq_def isnpoly_def split: tm.split poly.split)

lemma neq: "allpolys isnpoly p ==> Ifm vs bs (neq p) = Ifm vs bs (NEq p)"
  by (simp add: neq_def eq)

lemma lt_lin: "tmbound0 p ==> islin (lt p)"
  using islin_stupid
  by(auto simp: lt_def isnpoly_def split: tm.split poly.split)

lemma le_lin: "tmbound0 p ==> islin (le p)"
  using islin_stupid
  by(auto simp: le_def isnpoly_def split: tm.split poly.split)

lemma eq_lin: "tmbound0 p ==> islin (eq p)"
  using islin_stupid
  by(auto simp: eq_def isnpoly_def split: tm.split poly.split)

lemma neq_lin: "tmbound0 p ==> islin (neq p)"
  using islin_stupid
  by(auto simp: neq_def eq_def isnpoly_def split: tm.split poly.split)

definition "simplt t = (let (c,s) = split0 (simptm t) in if c= 0🪙p then lt s else Lt (CNP 0 c s))"
definition "simple t = (let (c,s) = split0 (simptm t) in if c= 0🪙p then le s else Le (CNP 0 c s))"
definition "simpeq t = (let (c,s) = split0 (simptm t) in if c= 0🪙p then eq s else Eq (CNP 0 c s))"
definition "simpneq t = (let (c,s) = split0 (simptm t) in if c= 0🪙p then neq s else NEq (CNP 0 c s))"

lemma simplt_islin [simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "islin (simplt t)"
  unfolding simplt_def
  using split0_nb0'
  by (auto simp: lt_lin Let_def split_def isnpoly_fst_split0[OF simptm_allpolys_npoly]
      islin_stupid allpolys_split0[OF simptm_allpolys_npoly])

lemma simple_islin [simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "islin (simple t)"
  unfolding simple_def
  using split0_nb0'
  by (auto simp: Let_def split_def isnpoly_fst_split0[OF simptm_allpolys_npoly]
      islin_stupid allpolys_split0[OF simptm_allpolys_npoly] le_lin)

lemma simpeq_islin [simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "islin (simpeq t)"
  unfolding simpeq_def
  using split0_nb0'
  by (auto simp: Let_def split_def isnpoly_fst_split0[OF simptm_allpolys_npoly]
      islin_stupid allpolys_split0[OF simptm_allpolys_npoly] eq_lin)

lemma simpneq_islin [simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "islin (simpneq t)"
  unfolding simpneq_def
  using split0_nb0'
  by (auto simp: Let_def split_def isnpoly_fst_split0[OF simptm_allpolys_npoly]
      islin_stupid allpolys_split0[OF simptm_allpolys_npoly] neq_lin)

lemma really_stupid: "¬ (∀c1 s'. (c1, s') ≠ split0 s)"
  by (cases "split0 s") auto

lemma split0_npoly:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
    and *: "allpolys isnpoly t"
  shows "isnpoly (fst (split0 t))"
    and "allpolys isnpoly (snd (split0 t))"
  using *
  by (induct t rule: split0.induct)
    (auto simp: Let_def split_def polyadd_norm polymul_norm polyneg_norm
      polysub_norm really_stupid)

lemma simplt[simp]: "Ifm vs bs (simplt t) = Ifm vs bs (Lt t)"
proof -
  have *: "allpolys isnpoly (simptm t)"
    by simp
  let ?t = "simptm t"
  show ?thesis
  proof (cases "fst (split0 ?t) = 0🪙p")
    case True
    then show ?thesis
      using split0[of "simptm t" vs bs] lt[OF split0_npoly(2)[OF *], of vs bs]
      by (simp add: simplt_def Let_def split_def lt)
  next
    case False
    then show ?thesis
      using split0[of "simptm t" vs bs]
      by (simp add: simplt_def Let_def split_def)
  qed
qed

lemma simple[simp]: "Ifm vs bs (simple t) = Ifm vs bs (Le t)"
proof -
  have *: "allpolys isnpoly (simptm t)"
    by simp
  let ?t = "simptm t"
  show ?thesis
  proof (cases "fst (split0 ?t) = 0🪙p")
    case True
    then show ?thesis
      using split0[of "simptm t" vs bs] le[OF split0_npoly(2)[OF *], of vs bs]
      by (simp add: simple_def Let_def split_def le)
  next
    case False
    then show ?thesis
      using split0[of "simptm t" vs bs]
      by (simp add: simple_def Let_def split_def)
  qed
qed

lemma simpeq[simp]: "Ifm vs bs (simpeq t) = Ifm vs bs (Eq t)"
proof -
  have n: "allpolys isnpoly (simptm t)"
    by simp
  let ?t = "simptm t"
  show ?thesis
  proof (cases "fst (split0 ?t) = 0🪙p")
    case True
    then show ?thesis
      using split0[of "simptm t" vs bs] eq[OF split0_npoly(2)[OF n], of vs bs]
      by (simp add: simpeq_def Let_def split_def)
  next
    case False
    then show ?thesis using  split0[of "simptm t" vs bs]
      by (simp add: simpeq_def Let_def split_def)
  qed
qed

lemma simpneq[simp]: "Ifm vs bs (simpneq t) = Ifm vs bs (NEq t)"
proof -
  have n: "allpolys isnpoly (simptm t)"
    by simp
  let ?t = "simptm t"
  show ?thesis
  proof (cases "fst (split0 ?t) = 0🪙p")
    case True
    then show ?thesis
      using split0[of "simptm t" vs bs] neq[OF split0_npoly(2)[OF n], of vs bs]
      by (simp add: simpneq_def Let_def split_def)
  next
    case False
    then show ?thesis
      using split0[of "simptm t" vs bs] by (simp add: simpneq_def Let_def split_def)
  qed
qed

lemma lt_nb: "tmbound0 t ==> bound0 (lt t)"
  by(auto simp: lt_def split: tm.split poly.split)

lemma le_nb: "tmbound0 t ==> bound0 (le t)"
  by(auto simp: le_def split: tm.split poly.split)

lemma eq_nb: "tmbound0 t ==> bound0 (eq t)"
  by(auto simp: eq_def split: tm.split poly.split)

lemma neq_nb: "tmbound0 t ==> bound0 (neq t)"
  by(auto simp: neq_def eq_def split: tm.split poly.split)

(*THE FOLLOWING PROOFS MIGHT BE COMBINED*)
lemma simplt_nb[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)" and t: "tmbound0 t"
  shows "bound0 (simplt t)"
proof (simp add: simplt_def Let_def split_def)
  have *: "tmbound0 (simptm t)"
    using t by simp
  let ?c = "fst (split0 (simptm t))"
  from tmbound_split0[OF *[unfolded tmbound0_tmbound_iff[symmetric]]]
  have th: "∀bs. Ipoly bs ?c = Ipoly bs 0🪙p"
    by auto
  from isnpoly_fst_split0[OF simptm_allpolys_npoly[of t]]
  have ths: "isnpolyh ?c 0" "isnpolyh 0🪙p 0"
    by (simp_all add: isnpoly_def)
  from iffD1[OF isnpolyh_unique[OF ths] th]
  have "fst (split0 (simptm t)) = 0🪙p" .
  then show "(fst (split0 (simptm t)) = 0🪙p ⟶ bound0 (lt (snd (split0 (simptm t))))) ∧
      fst (split0 (simptm t)) = 0🪙p"
    by (simp add: simplt_def Let_def split_def lt_nb)
qed

lemma simple_nb[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)" and t: "tmbound0 t"
  shows "bound0 (simple t)"
proof(simp add: simple_def Let_def split_def)
  have *: "tmbound0 (simptm t)"
    using t by simp
  let ?c = "fst (split0 (simptm t))"
  from tmbound_split0[OF *[unfolded tmbound0_tmbound_iff[symmetric]]]
  have th: "∀bs. Ipoly bs ?c = Ipoly bs 0🪙p"
    by auto
  from isnpoly_fst_split0[OF simptm_allpolys_npoly[of t]]
  have ths: "isnpolyh ?c 0" "isnpolyh 0🪙p 0"
    by (simp_all add: isnpoly_def)
  from iffD1[OF isnpolyh_unique[OF ths] th]
  have "fst (split0 (simptm t)) = 0🪙p" .
  then show "(fst (split0 (simptm t)) = 0🪙p ⟶ bound0 (le (snd (split0 (simptm t))))) ∧
      fst (split0 (simptm t)) = 0🪙p"
    by (simp add: simplt_def Let_def split_def le_nb)
qed

lemma simpeq_nb[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)" and t: "tmbound0 t"
  shows "bound0 (simpeq t)"
proof (simp add: simpeq_def Let_def split_def)
  have *: "tmbound0 (simptm t)"
    using t by simp
  let ?c = "fst (split0 (simptm t))"
  from tmbound_split0[OF *[unfolded tmbound0_tmbound_iff[symmetric]]]
  have th: "∀bs. Ipoly bs ?c = Ipoly bs 0🪙p"
    by auto
  from isnpoly_fst_split0[OF simptm_allpolys_npoly[of t]]
  have ths: "isnpolyh ?c 0" "isnpolyh 0🪙p 0"
    by (simp_all add: isnpoly_def)
  from iffD1[OF isnpolyh_unique[OF ths] th]
  have "fst (split0 (simptm t)) = 0🪙p" .
  then show "(fst (split0 (simptm t)) = 0🪙p ⟶ bound0 (eq (snd (split0 (simptm t))))) ∧
      fst (split0 (simptm t)) = 0🪙p"
    by (simp add: simpeq_def Let_def split_def eq_nb)
qed

lemma simpneq_nb[simp]:
  assumes "SORT_CONSTRAINT('a::field_char_0)" and t: "tmbound0 t"
  shows "bound0 (simpneq t)"
proof (simp add: simpneq_def Let_def split_def)
  have *: "tmbound0 (simptm t)"
    using t by simp
  let ?c = "fst (split0 (simptm t))"
  from tmbound_split0[OF *[unfolded tmbound0_tmbound_iff[symmetric]]]
  have th: "∀bs. Ipoly bs ?c = Ipoly bs 0🪙p"
    by auto
  from isnpoly_fst_split0[OF simptm_allpolys_npoly[of t]]
  have ths: "isnpolyh ?c 0" "isnpolyh 0🪙p 0"
    by (simp_all add: isnpoly_def)
  from iffD1[OF isnpolyh_unique[OF ths] th]
  have "fst (split0 (simptm t)) = 0🪙p" .
  then show "(fst (split0 (simptm t)) = 0🪙p ⟶ bound0 (neq (snd (split0 (simptm t))))) ∧
      fst (split0 (simptm t)) = 0🪙p"
    by (simp add: simpneq_def Let_def split_def neq_nb)
qed

fun conjs :: "fm ==> fm list"
  where
    "conjs (And p q) = conjs p @ conjs q"
  | "conjs T = []"
  | "conjs p = [p]"

lemma conjs_ci: "(∀q ∈ set (conjs p). Ifm vs bs q) = Ifm vs bs p"
  by (induct p rule: conjs.induct) auto

definition list_disj :: "fm list ==> fm"
  where "list_disj ps ≡ foldr disj ps F"

lemma list_conj: "Ifm vs bs (list_conj ps) = (∀p∈ set ps. Ifm vs bs p)"
  by (induct ps) (auto simp: list_conj_def)

lemma list_conj_qf: " ∀p∈ set ps. qfree p ==> qfree (list_conj ps)"
  by (induct ps) (auto simp: list_conj_def)

lemma list_disj: "Ifm vs bs (list_disj ps) = (∃p∈ set ps. Ifm vs bs p)"
  by (induct ps) (auto simp: list_disj_def)

lemma conj_boundslt: "boundslt n p ==> boundslt n q ==> boundslt n (conj p q)"
  unfolding conj_def by auto

lemma conjs_nb: "bound n p ==> ∀q∈ set (conjs p). bound n q"
proof (induct p rule: conjs.induct)
  case (1 p q)
  then show ?case 
    unfolding conjs.simps bound.simps by fastforce
qed auto

lemma conjs_boundslt: "boundslt n p ==> ∀q∈ set (conjs p). boundslt n q"
proof (induct p rule: conjs.induct)
  case (1 p q)
  then show ?case 
    unfolding conjs.simps bound.simps by fastforce
qed auto

lemma list_conj_boundslt: " ∀p∈ set ps. boundslt n p ==> boundslt n (list_conj ps)"
  by (induct ps) (auto simp: list_conj_def)

lemma list_conj_nb:
  assumes "∀p∈ set ps. bound n p"
  shows "bound n (list_conj ps)"
  using assms by (induct ps) (auto simp: list_conj_def)

lemma list_conj_nb': "∀p∈set ps. bound0 p ==> bound0 (list_conj ps)"
  by (induct ps) (auto simp: list_conj_def)

lemma CJNB_qe:
  assumes qe: "∀bs p. qfree p ⟶ qfree (qe p) ∧ (Ifm vs bs (qe p) = Ifm vs bs (E p))"
  shows "∀bs p. qfree p ⟶ qfree (CJNB qe p) ∧ (Ifm vs bs ((CJNB qe p)) = Ifm vs bs (E p))"
proof clarify
  fix bs p
  assume qfp: "qfree p"
  let ?cjs = "conjuncts p"
  let ?yes = "fst (partition bound0 ?cjs)"
  let ?no = "snd (partition bound0 ?cjs)"
  let ?cno = "list_conj ?no"
  let ?cyes = "list_conj ?yes"
  have part: "partition bound0 ?cjs = (?yes,?no)"
    by simp
  from partition_P[OF part] have "∀q∈ set ?yes. bound0 q"
    by blast
  then have yes_nb: "bound0 ?cyes"
    by (simp add: list_conj_nb')
  then have yes_qf: "qfree (decr0 ?cyes)"
    by (simp add: decr0_qf)
  from conjuncts_qf[OF qfp] partition_set[OF part]
  have " ∀q∈ set ?no. qfree q"
    by auto
  then have no_qf: "qfree ?cno"
    by (simp add: list_conj_qf)
  with qe have cno_qf:"qfree (qe ?cno)"
    and noE: "Ifm vs bs (qe ?cno) = Ifm vs bs (E ?cno)"
    by blast+
  from cno_qf yes_qf have qf: "qfree (CJNB qe p)"
    by (simp add: CJNB_def Let_def split_def)
  have "Ifm vs bs p = ((Ifm vs bs ?cyes) ∧ (Ifm vs bs ?cno))" for bs
  proof -
    from conjuncts have "Ifm vs bs p = (∀q∈ set ?cjs. Ifm vs bs q)"
      by blast
    also have "… = ((∀q∈ set ?yes. Ifm vs bs q) ∧ (∀q∈ set ?no. Ifm vs bs q))"
      using partition_set[OF part] by auto
    finally show ?thesis
      using list_conj[of vs bs] by simp
  qed
  then have "Ifm vs bs (E p) = (∃x. (Ifm vs (x#bs) ?cyes) ∧ (Ifm vs (x#bs) ?cno))"
    by simp
  also fix y have "… = (∃x. (Ifm vs (y#bs) ?cyes) ∧ (Ifm vs (x#bs) ?cno))"
    using bound0_I[OF yes_nb, where bs="bs" and b'="y"] by blast
  also have "… = (Ifm vs bs (decr0 ?cyes) ∧ Ifm vs bs (E ?cno))"
    by (auto simp: decr0[OF yes_nb] simp del: partition_filter_conv)
  also have "… = (Ifm vs bs (conj (decr0 ?cyes) (qe ?cno)))"
    using qe[rule_format, OF no_qf] by auto
  finally have "Ifm vs bs (E p) = Ifm vs bs (CJNB qe p)"
    by (simp add: Let_def CJNB_def split_def)
  with qf show "qfree (CJNB qe p) ∧ Ifm vs bs (CJNB qe p) = Ifm vs bs (E p)"
    by blast
qed

fun simpfm :: "fm ==> fm"
  where
    "simpfm (Lt t) = simplt (simptm t)"
  | "simpfm (Le t) = simple (simptm t)"
  | "simpfm (Eq t) = simpeq(simptm t)"
  | "simpfm (NEq t) = simpneq(simptm t)"
  | "simpfm (And p q) = conj (simpfm p) (simpfm q)"
  | "simpfm (Or p q) = disj (simpfm p) (simpfm q)"
  | "simpfm (Imp p q) = disj (simpfm (Not p)) (simpfm q)"
  | "simpfm (Iff p q) =
      disj (conj (simpfm p) (simpfm q)) (conj (simpfm (Not p)) (simpfm (Not q)))"
  | "simpfm (Not (And p q)) = disj (simpfm (Not p)) (simpfm (Not q))"
  | "simpfm (Not (Or p q)) = conj (simpfm (Not p)) (simpfm (Not q))"
  | "simpfm (Not (Imp p q)) = conj (simpfm p) (simpfm (Not q))"
  | "simpfm (Not (Iff p q)) =
      disj (conj (simpfm p) (simpfm (Not q))) (conj (simpfm (Not p)) (simpfm q))"
  | "simpfm (Not (Eq t)) = simpneq t"
  | "simpfm (Not (NEq t)) = simpeq t"
  | "simpfm (Not (Le t)) = simplt (Neg t)"
  | "simpfm (Not (Lt t)) = simple (Neg t)"
  | "simpfm (Not (Not p)) = simpfm p"
  | "simpfm (Not T) = F"
  | "simpfm (Not F) = T"
  | "simpfm p = p"

lemma simpfm[simp]: "Ifm vs bs (simpfm p) = Ifm vs bs p"
  by (induct p arbitrary: bs rule: simpfm.induct) auto

lemma simpfm_bound0:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "bound0 p ==> bound0 (simpfm p)"
  by (induct p rule: simpfm.induct) auto

lemma lt_qf[simp]: "qfree (lt t)"
  by(auto simp: lt_def split: tm.split poly.split)

lemma le_qf[simp]: "qfree (le t)"
  by(auto simp: le_def split: tm.split poly.split)

lemma eq_qf[simp]: "qfree (eq t)"
  by(auto simp: eq_def split: tm.split poly.split)

lemma neq_qf[simp]: "qfree (neq t)"
  by (simp add: neq_def)

lemma simplt_qf[simp]: "qfree (simplt t)"
  by (simp add: simplt_def Let_def split_def)

lemma simple_qf[simp]: "qfree (simple t)"
  by (simp add: simple_def Let_def split_def)

lemma simpeq_qf[simp]: "qfree (simpeq t)"
  by (simp add: simpeq_def Let_def split_def)

lemma simpneq_qf[simp]: "qfree (simpneq t)"
  by (simp add: simpneq_def Let_def split_def)

lemma simpfm_qf[simp]: "qfree p ==> qfree (simpfm p)"
  by (induct p rule: simpfm.induct) auto

lemma disj_lin: "islin p ==> islin q ==> islin (disj p q)"
  by (simp add: disj_def)

lemma conj_lin: "islin p ==> islin q ==> islin (conj p q)"
  by (simp add: conj_def)

lemma
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "qfree p ==> islin (simpfm p)"
  by (induct p rule: simpfm.induct) (simp_all add: conj_lin disj_lin)

fun prep :: "fm ==> fm"
  where
    "prep (E T) = T"
  | "prep (E F) = F"
  | "prep (E (Or p q)) = disj (prep (E p)) (prep (E q))"
  | "prep (E (Imp p q)) = disj (prep (E (Not p))) (prep (E q))"
  | "prep (E (Iff p q)) = disj (prep (E (And p q))) (prep (E (And (Not p) (Not q))))"
  | "prep (E (Not (And p q))) = disj (prep (E (Not p))) (prep (E(Not q)))"
  | "prep (E (Not (Imp p q))) = prep (E (And p (Not q)))"
  | "prep (E (Not (Iff p q))) = disj (prep (E (And p (Not q)))) (prep (E(And (Not p) q)))"
  | "prep (E p) = E (prep p)"
  | "prep (A (And p q)) = conj (prep (A p)) (prep (A q))"
  | "prep (A p) = prep (Not (E (Not p)))"
  | "prep (Not (Not p)) = prep p"
  | "prep (Not (And p q)) = disj (prep (Not p)) (prep (Not q))"
  | "prep (Not (A p)) = prep (E (Not p))"
  | "prep (Not (Or p q)) = conj (prep (Not p)) (prep (Not q))"
  | "prep (Not (Imp p q)) = conj (prep p) (prep (Not q))"
  | "prep (Not (Iff p q)) = disj (prep (And p (Not q))) (prep (And (Not p) q))"
  | "prep (Not p) = not (prep p)"
  | "prep (Or p q) = disj (prep p) (prep q)"
  | "prep (And p q) = conj (prep p) (prep q)"
  | "prep (Imp p q) = prep (Or (Not p) q)"
  | "prep (Iff p q) = disj (prep (And p q)) (prep (And (Not p) (Not q)))"
  | "prep p = p"

lemma prep: "Ifm vs bs (prep p) = Ifm vs bs p"
  by (induct p arbitrary: bs rule: prep.induct) auto


text ‹Generic quantifier elimination.›
fun qelim :: "fm ==> (fm ==> fm) ==> fm"
  where
    "qelim (E p) = (λqe. DJ (CJNB qe) (qelim p qe))"
  | "qelim (A p) = (λqe. not (qe ((qelim (Not p) qe))))"
  | "qelim (Not p) = (λqe. not (qelim p qe))"
  | "qelim (And p q) = (λqe. conj (qelim p qe) (qelim q qe))"
  | "qelim (Or p q) = (λqe. disj (qelim p qe) (qelim q qe))"
  | "qelim (Imp p q) = (λqe. imp (qelim p qe) (qelim q qe))"
  | "qelim (Iff p q) = (λqe. iff (qelim p qe) (qelim q qe))"
  | "qelim p = (λy. simpfm p)"

lemma qelim:
  assumes qe_inv: "∀bs p. qfree p ⟶ qfree (qe p) ∧ (Ifm vs bs (qe p) = Ifm vs bs (E p))"
  shows "∧ bs. qfree (qelim p qe) ∧ (Ifm vs bs (qelim p qe) = Ifm vs bs p)"
  using qe_inv DJ_qe[OF CJNB_qe[OF qe_inv]]
  by (induct p rule: qelim.induct) auto


subsection ‹Core Procedure›

fun minusinf:: "fm ==> fm"  🍋 ‹virtual substitution of ‹-∞›\   where
    "minusinf (And p q) = conj (minusinf p) (minusinf q)"
  | "minusinf (Or p q) = disj (minusinf p) (minusinf q)"
  | "minusinf (Eq (CNP 0 c e)) = conj (eq (CP c)) (eq e)"
  | "minusinf (NEq (CNP 0 c e)) = disj (not (eq e)) (not (eq (CP c)))"
  | "minusinf (Lt (CNP 0 c e)) = disj (conj (eq (CP c)) (lt e)) (lt (CP (~🪙p c)))"
  | "minusinf (Le (CNP 0 c e)) = disj (conj (eq (CP c)) (le e)) (lt (CP (~🪙p c)))"
  | "minusinf p = p"

fun plusinf:: "fm ==> fm"  🍋 ‹virtual substitution of ‹+∞›\›
  where
    "plusinf (And p q) = conj (plusinf p) (plusinf q)"
  | "plusinf (Or p q) = disj (plusinf p) (plusinf q)"
  | "plusinf (Eq (CNP 0 c e)) = conj (eq (CP c)) (eq e)"
  | "plusinf (NEq (CNP 0 c e)) = disj (not (eq e)) (not (eq (CP c)))"
  | "plusinf (Lt (CNP 0 c e)) = disj (conj (eq (CP c)) (lt e)) (lt (CP c))"
  | "plusinf (Le (CNP 0 c e)) = disj (conj (eq (CP c)) (le e)) (lt (CP c))"
  | "plusinf p = p"

lemma minusinf_inf:
  assumes "islin p"
  shows "∃z. ∀x < z. Ifm vs (x#bs) (minusinf p) ⟷ Ifm vs (x#bs) p"
  using assms
proof (induct p rule: minusinf.induct)
  case (1 p q)
  then obtain zp zq where zp: "∀x
       and zq: "∀x
    by force
  then show ?case
    by (rule_tac x="min zp zq" in exI) auto
next
  case (2 p q)
  then obtain zp zq where zp: "∀x
       and zq: "∀x
    by force
  then show ?case
    by (rule_tac x="min zp zq" in exI) auto
next
  case (3 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 3 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  note eqs = eq[OF nc(1), where ?'a = 'a] eq[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using eq[OF nc(2), of vs] eq[OF nc(1), of vs] by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Eq (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Eq (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using pos_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x" and vs=vs and bs=bs] by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Eq (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Eq (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using neg_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] eqs by auto
    qed
    then show ?thesis by auto
  qed
next
  case (4 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 4 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  note eqs = eq[OF nc(1), where ?'a = 'a] eq[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0"
    by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (NEq (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (NEq (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using pos_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (NEq (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (NEq (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using neg_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] by auto
    qed
    then show ?thesis by auto
  qed
next
  case (5 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 5 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  then have nc': "allpolys isnpoly (CP (~🪙p c))"
    by (simp add: polyneg_norm)
  note eqs = lt[OF nc', where ?'a = 'a] eq [OF nc(1), where ?'a = 'a] lt[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0"
    by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Lt (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Lt (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using pos_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0" by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Lt (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Lt (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using neg_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] c by auto
    qed
    then show ?thesis by auto
  qed
next
  case (6 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 6 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  then have nc': "allpolys isnpoly (CP (~🪙p c))"
    by (simp add: polyneg_norm)
  note eqs = lt[OF nc', where ?'a = 'a] eq [OF nc(1), where ?'a = 'a] le[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Le (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Le (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using pos_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs
        by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Le (CNP 0 c e)) = Ifm vs (x#bs) (minusinf (Le (CNP 0 c e)))"
      if "x < -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using neg_less_divide_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs
        by auto
    qed
    then show ?thesis by auto
  qed
qed auto

lemma plusinf_inf:
  assumes "islin p"
  shows "∃z. ∀x > z. Ifm vs (x#bs) (plusinf p) ⟷ Ifm vs (x#bs) p"
  using assms
proof (induct p rule: plusinf.induct)
  case (1 p q)
  then obtain zp zq where zp: "∀x>zp. Ifm vs (x # bs) (plusinf p) = Ifm vs (x # bs) p"
       and zq: "∀x>zq. Ifm vs (x # bs) (plusinf q) = Ifm vs (x # bs) q"
    by force
  then show ?case
    by (rule_tac x="max zp zq" in exI) auto
next
  case (2 p q)
  then obtain zp zq where zp: "∀x>zp. Ifm vs (x # bs) (plusinf p) = Ifm vs (x # bs) p"
       and zq: "∀x>zq. Ifm vs (x # bs) (plusinf q) = Ifm vs (x # bs) q"
    by force
  then show ?case
    by (rule_tac x="max zp zq" in exI) auto
next
  case (3 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 3 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  note eqs = eq[OF nc(1), where ?'a = 'a] eq[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using eq[OF nc(2), of vs] eq[OF nc(1), of vs] by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Eq (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Eq (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using pos_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x" and vs=vs and bs=bs] by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Eq (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Eq (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using neg_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0" by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] eqs by auto
    qed
    then show ?thesis by auto
  qed
next
  case (4 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 4 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  note eqs = eq[OF nc(1), where ?'a = 'a] eq[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (NEq (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (NEq (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using pos_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (NEq (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (NEq (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using neg_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] by auto
    qed
    then show ?thesis by auto
  qed
next
  case (5 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 5 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  then have nc': "allpolys isnpoly (CP (~🪙p c))"
    by (simp add: polyneg_norm)
  note eqs = lt[OF nc(1), where ?'a = 'a] lt[OF nc', where ?'a = 'a] eq [OF nc(1), where ?'a = 'a] lt[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Lt (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Lt (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using pos_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Lt (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Lt (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using neg_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using eqs tmbound0_I[OF nbe, where b="y" and b'="x"] c by auto
    qed
    then show ?thesis by auto
  qed
next
  case (6 c e)
  then have nbe: "tmbound0 e"
    by simp
  from 6 have nc: "allpolys isnpoly (CP c)" "allpolys isnpoly e"
    by simp_all
  then have nc': "allpolys isnpoly (CP (~🪙p c))"
    by (simp add: polyneg_norm)
  note eqs = lt[OF nc(1), where ?'a = 'a] eq [OF nc(1), where ?'a = 'a] le[OF nc(2), where ?'a = 'a]
  let ?c = "Ipoly vs c"
  fix y
  let ?e = "Itm vs (y#bs) e"
  consider "?c = 0" | "?c > 0" | "?c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis using eqs by auto
  next
    case c: 2
    have "Ifm vs (x#bs) (Le (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Le (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x > - ?e"
        using pos_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e > 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs by auto
    qed
    then show ?thesis by auto
  next
    case c: 3
    have "Ifm vs (x#bs) (Le (CNP 0 c e)) = Ifm vs (x#bs) (plusinf (Le (CNP 0 c e)))"
      if "x > -?e / ?c" for x
    proof -
      from that have "?c * x < - ?e"
        using neg_divide_less_eq[OF c, where a="x" and b="-?e"]
        by (simp add: mult.commute)
      then have "?c * x + ?e < 0"
        by simp
      then show ?thesis
        using tmbound0_I[OF nbe, where b="y" and b'="x"] c eqs by auto
    qed
    then show ?thesis by auto
  qed
qed auto

lemma minusinf_nb: "islin p ==> bound0 (minusinf p)"
  by (induct p rule: minusinf.induct) (auto simp: eq_nb lt_nb le_nb)

lemma plusinf_nb: "islin p ==> bound0 (plusinf p)"
  by (induct p rule: minusinf.induct) (auto simp: eq_nb lt_nb le_nb)

lemma minusinf_ex:
  assumes lp: "islin p"
    and ex: "Ifm vs (x#bs) (minusinf p)"
  shows "∃x. Ifm vs (x#bs) p"
proof -
  from bound0_I [OF minusinf_nb[OF lp], where bs ="bs"] ex
  have th: "∀x. Ifm vs (x#bs) (minusinf p)"
    by auto
  from minusinf_inf[OF lp, where bs="bs"]
  obtain z where z: "∀x
    by blast
  from th have "Ifm vs ((z - 1)#bs) (minusinf p)"
    by simp
  moreover have "z - 1 < z"
    by simp
  ultimately show ?thesis
    using z by auto
qed

lemma plusinf_ex:
  assumes lp: "islin p"
    and ex: "Ifm vs (x#bs) (plusinf p)"
  shows "∃x. Ifm vs (x#bs) p"
proof -
  from bound0_I [OF plusinf_nb[OF lp], where bs ="bs"] ex
  have th: "∀x. Ifm vs (x#bs) (plusinf p)"
    by auto
  from plusinf_inf[OF lp, where bs="bs"]
  obtain z where z: "∀x>z. Ifm vs (x # bs) (plusinf p) = Ifm vs (x # bs) p"
    by blast
  from th have "Ifm vs ((z + 1)#bs) (plusinf p)"
    by simp
  moreover have "z + 1 > z"
    by simp
  ultimately show ?thesis
    using z by auto
qed

fun uset :: "fm ==> (poly × tm) list"
  where
    "uset (And p q) = uset p @ uset q"
  | "uset (Or p q) = uset p @ uset q"
  | "uset (Eq (CNP 0 a e)) = [(a, e)]"
  | "uset (Le (CNP 0 a e)) = [(a, e)]"
  | "uset (Lt (CNP 0 a e)) = [(a, e)]"
  | "uset (NEq (CNP 0 a e)) = [(a, e)]"
  | "uset p = []"

lemma uset_l:
  assumes lp: "islin p"
  shows "∀(c,s) ∈ set (uset p). isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s"
  using lp by (induct p rule: uset.induct) auto

lemma minusinf_uset0:
  assumes lp: "islin p"
    and nmi: "¬ (Ifm vs (x#bs) (minusinf p))"
    and ex: "Ifm vs (x#bs) p" (is "?I x p")
  shows "∃(c, s) ∈ set (uset p). x ≥ - Itm vs (x#bs) s / Ipoly vs c"
proof -
  have "∃(c, s) ∈ set (uset p).
      Ipoly vs c < 0 ∧ Ipoly vs c * x ≤ - Itm vs (x#bs) s ∨
      Ipoly vs c > 0 ∧ Ipoly vs c * x ≥ - Itm vs (x#bs) s"
    using lp nmi ex
    by (induct p rule: minusinf.induct)
       (auto simp: eq le lt polyneg_norm linorder_not_less order_le_less)
  then obtain c s where csU: "(c, s) ∈ set (uset p)"
    and x: "(Ipoly vs c < 0 ∧ Ipoly vs c * x ≤ - Itm vs (x#bs) s) ∨
      (Ipoly vs c > 0 ∧ Ipoly vs c * x ≥ - Itm vs (x#bs) s)" by blast
  then have "x ≥ (- Itm vs (x#bs) s) / Ipoly vs c"
    using divide_le_eq[of "- Itm vs (x#bs) s" "Ipoly vs c" x]
    by (auto simp: mult.commute)
  then show ?thesis
    using csU by auto
qed

lemma minusinf_uset:
  assumes lp: "islin p"
    and nmi: "¬ (Ifm vs (a#bs) (minusinf p))"
    and ex: "Ifm vs (x#bs) p" (is "?I x p")
  shows "∃(c,s) ∈ set (uset p). x ≥ - Itm vs (a#bs) s / Ipoly vs c"
proof -
  from nmi have nmi': "¬ Ifm vs (x#bs) (minusinf p)"
    by (simp add: bound0_I[OF minusinf_nb[OF lp], where b=x and b'=a])
  from minusinf_uset0[OF lp nmi' ex]
  obtain c s where csU: "(c,s) ∈ set (uset p)"
    and th: "x ≥ - Itm vs (x#bs) s / Ipoly vs c"
    by blast
  from uset_l[OF lp, rule_format, OF csU] have nb: "tmbound0 s"
    by simp
  from th tmbound0_I[OF nb, of vs x bs a] csU show ?thesis
    by auto
qed


lemma plusinf_uset0:
  assumes lp: "islin p"
    and nmi: "¬ (Ifm vs (x#bs) (plusinf p))"
    and ex: "Ifm vs (x#bs) p" (is "?I x p")
  shows "∃(c, s) ∈ set (uset p). x ≤ - Itm vs (x#bs) s / Ipoly vs c"
proof -
  have "∃(c, s) ∈ set (uset p).
      Ipoly vs c < 0 ∧ Ipoly vs c * x ≥ - Itm vs (x#bs) s ∨
      Ipoly vs c > 0 ∧ Ipoly vs c * x ≤ - Itm vs (x#bs) s"
    using lp nmi ex
    by (induct p rule: minusinf.induct)
       (auto simp: eq le lt polyneg_norm linorder_not_less order_le_less)
  then obtain c s
    where c_s: "(c, s) ∈ set (uset p)"
      and "Ipoly vs c < 0 ∧ Ipoly vs c * x ≥ - Itm vs (x#bs) s ∨
        Ipoly vs c > 0 ∧ Ipoly vs c * x ≤ - Itm vs (x#bs) s"
    by blast
  then have "x ≤ (- Itm vs (x#bs) s) / Ipoly vs c"
    using le_divide_eq[of x "- Itm vs (x#bs) s" "Ipoly vs c"]
    by (auto simp: mult.commute)
  then show ?thesis
    using c_s by auto
qed

lemma plusinf_uset:
  assumes lp: "islin p"
    and nmi: "¬ (Ifm vs (a#bs) (plusinf p))"
    and ex: "Ifm vs (x#bs) p" (is "?I x p")
  shows "∃(c,s) ∈ set (uset p). x ≤ - Itm vs (a#bs) s / Ipoly vs c"
proof -
  from nmi have nmi': "¬ (Ifm vs (x#bs) (plusinf p))"
    by (simp add: bound0_I[OF plusinf_nb[OF lp], where b=x and b'=a])
  from plusinf_uset0[OF lp nmi' ex]
  obtain c s
    where c_s: "(c,s) ∈ set (uset p)"
      and x: "x ≤ - Itm vs (x#bs) s / Ipoly vs c"
    by blast
  from uset_l[OF lp, rule_format, OF c_s] have nb: "tmbound0 s"
    by simp
  from x tmbound0_I[OF nb, of vs x bs a] c_s show ?thesis
    by auto
qed

lemma lin_dense:
  assumes lp: "islin p"
    and noS: "∀t. l < t ∧ t< u ⟶ t ∉ (λ(c,t). - Itm vs (x#bs) t / Ipoly vs c) ` set (uset p)"
      (is "∀t. _ ∧ _ ⟶ t ∉ (λ(c,t). - ?Nt x t / ?N c) ` ?U p")
    and lx: "l < x" and xu: "x < u"
    and px: "Ifm vs (x # bs) p"
    and ly: "l < y" and yu: "y < u"
  shows "Ifm vs (y#bs) p"
  using lp px noS
proof (induct p rule: islin.induct)
  case (5 c s)
  from "5.prems"
  have lin: "isnpoly c" "c ≠ 0🪙p" "tmbound0 s" "allpolys isnpoly s"
    and px: "Ifm vs (x # bs) (Lt (CNP 0 c s))"
    and noS: "∀t. l < t ∧ t < u ⟶ t ≠ - Itm vs (x # bs) s / (c)🪙p🪙vs🪙"
    by simp_all
  from ly yu noS have yne: "y ≠ - ?Nt x s / (c)🪙p🪙vs🪙"
    by simp
  then have ycs: "y < - ?Nt x s / ?N c ∨ y > -?Nt x s / ?N c"
    by auto
  consider "?N c = 0" | "?N c > 0" | "?N c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using px by (simp add: tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"])
  next
    case N: 2
    from px pos_less_divide_eq[OF N, where a="x" and b="-?Nt x s"]
    have px': "x < - ?Nt x s / ?N c"
      by (auto simp: not_less field_simps)
    from ycs show ?thesis
    proof
      assume y: "y < - ?Nt x s / ?N c"
      then have "y * ?N c < - ?Nt x s"
        by (simp add: pos_less_divide_eq[OF N, where a="y" and b="-?Nt x s", symmetric])
      then have "?N c * y + ?Nt x s < 0"
        by (simp add: field_simps)
      then show ?thesis using tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"]
        by simp
    next
      assume y: "y > -?Nt x s / ?N c"
      with yu have eu: "u > - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≤ l"
        by (cases "- ?Nt x s / ?N c > l") auto
      with lx px' have False
        by simp
      then show ?thesis ..
    qed
  next
    case N: 3
    from px neg_divide_less_eq[OF N, where a="x" and b="-?Nt x s"]
    have px': "x > - ?Nt x s / ?N c"
      by (auto simp: not_less field_simps)
    from ycs show ?thesis
    proof
      assume y: "y > - ?Nt x s / ?N c"
      then have "y * ?N c < - ?Nt x s"
        by (simp add: neg_divide_less_eq[OF N, where a="y" and b="-?Nt x s", symmetric])
      then have "?N c * y + ?Nt x s < 0"
        by (simp add: field_simps)
      then show ?thesis using tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"]
        by simp
    next
      assume y: "y < -?Nt x s / ?N c"
      with ly have eu: "l < - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≥ u"
        by (cases "- ?Nt x s / ?N c < u") auto
      with xu px' have False
        by simp
      then show ?thesis ..
    qed
  qed
next
  case (6 c s)
  from "6.prems"
  have lin: "isnpoly c" "c ≠ 0🪙p" "tmbound0 s" "allpolys isnpoly s"
    and px: "Ifm vs (x # bs) (Le (CNP 0 c s))"
    and noS: "∀t. l < t ∧ t < u ⟶ t ≠ - Itm vs (x # bs) s / (c)🪙p🪙vs🪙"
    by simp_all
  from ly yu noS have yne: "y ≠ - ?Nt x s / (c)🪙p🪙vs🪙"
    by simp
  then have ycs: "y < - ?Nt x s / ?N c ∨ y > -?Nt x s / ?N c"
    by auto
  have ccs: "?N c = 0 ∨ ?N c < 0 ∨ ?N c > 0" by dlo
  consider "?N c = 0" | "?N c > 0" | "?N c < 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using px by (simp add: tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"])
  next
    case N: 2
    from px pos_le_divide_eq[OF N, where a="x" and b="-?Nt x s"]
    have px': "x ≤ - ?Nt x s / ?N c"
      by (simp add: not_less field_simps)
    from ycs show ?thesis
    proof
      assume y: "y < - ?Nt x s / ?N c"
      then have "y * ?N c < - ?Nt x s"
        by (simp add: pos_less_divide_eq[OF N, where a="y" and b="-?Nt x s", symmetric])
      then have "?N c * y + ?Nt x s < 0"
        by (simp add: field_simps)
      then show ?thesis
        using tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"] by simp
    next
      assume y: "y > -?Nt x s / ?N c"
      with yu have eu: "u > - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≤ l"
        by (cases "- ?Nt x s / ?N c > l") auto
      with lx px' have False
        by simp
      then show ?thesis ..
    qed
  next
    case N: 3
    from px neg_divide_le_eq[OF N, where a="x" and b="-?Nt x s"]
    have px': "x ≥ - ?Nt x s / ?N c"
      by (simp add: field_simps)
    from ycs show ?thesis
    proof
      assume y: "y > - ?Nt x s / ?N c"
      then have "y * ?N c < - ?Nt x s"
        by (simp add: neg_divide_less_eq[OF N, where a="y" and b="-?Nt x s", symmetric])
      then have "?N c * y + ?Nt x s < 0"
        by (simp add: field_simps)
      then show ?thesis
        using tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"] by simp
    next
      assume y: "y < -?Nt x s / ?N c"
      with ly have eu: "l < - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≥ u"
        by (cases "- ?Nt x s / ?N c < u") auto
      with xu px' have False by simp
      then show ?thesis ..
    qed
  qed
next
  case (3 c s)
  from "3.prems"
  have lin: "isnpoly c" "c ≠ 0🪙p" "tmbound0 s" "allpolys isnpoly s"
    and px: "Ifm vs (x # bs) (Eq (CNP 0 c s))"
    and noS: "∀t. l < t ∧ t < u ⟶ t ≠ - Itm vs (x # bs) s / (c)🪙p🪙vs🪙"
    by simp_all
  from ly yu noS have yne: "y ≠ - ?Nt x s / (c)🪙p🪙vs🪙"
    by simp
  then have ycs: "y < - ?Nt x s / ?N c ∨ y > -?Nt x s / ?N c"
    by auto
  consider "?N c = 0" | "?N c < 0" | "?N c > 0" by arith
  then show ?case
  proof cases
    case 1
    then show ?thesis
      using px by (simp add: tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"])
  next
    case 2
    then have cnz: "?N c ≠ 0"
      by simp
    from px eq_divide_eq[of "x" "-?Nt x s" "?N c"] cnz
    have px': "x = - ?Nt x s / ?N c"
      by (simp add: field_simps)
    from ycs show ?thesis
    proof
      assume y: "y < -?Nt x s / ?N c"
      with ly have eu: "l < - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≥ u"
        by (cases "- ?Nt x s / ?N c < u") auto
      with xu px' have False by simp
      then show ?thesis ..
    next
      assume y: "y > -?Nt x s / ?N c"
      with yu have eu: "u > - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≤ l"
        by (cases "- ?Nt x s / ?N c > l") auto
      with lx px' have False by simp
      then show ?thesis ..
    qed
  next
    case 3
    then have cnz: "?N c ≠ 0"
      by simp
    from px eq_divide_eq[of "x" "-?Nt x s" "?N c"] cnz
    have px': "x = - ?Nt x s / ?N c"
      by (simp add: field_simps)
    from ycs show ?thesis
    proof
      assume y: "y < -?Nt x s / ?N c"
      with ly have eu: "l < - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≥ u"
        by (cases "- ?Nt x s / ?N c < u") auto
      with xu px' have False by simp
      then show ?thesis ..
    next
      assume y: "y > -?Nt x s / ?N c"
      with yu have eu: "u > - ?Nt x s / ?N c"
        by auto
      with noS ly yu have th: "- ?Nt x s / ?N c ≤ l"
        by (cases "- ?Nt x s / ?N c > l") auto
      with lx px' have False by simp
      then show ?thesis ..
    qed
  qed
next
  case (4 c s)
  from "4.prems"
  have lin: "isnpoly c" "c ≠ 0🪙p" "tmbound0 s" "allpolys isnpoly s"
    and px: "Ifm vs (x # bs) (NEq (CNP 0 c s))"
    and noS: "∀t. l < t ∧ t < u ⟶ t ≠ - Itm vs (x # bs) s / (c)🪙p🪙vs🪙"
    by simp_all
  from ly yu noS have yne: "y ≠ - ?Nt x s / (c)🪙p🪙vs🪙"
    by simp
  then have ycs: "y < - ?Nt x s / ?N c ∨ y > -?Nt x s / ?N c"
    by auto
  show ?case
  proof (cases "?N c = 0")
    case True
    then show ?thesis
      using px by (simp add: tmbound0_I[OF lin(3), where bs="bs" and b="x" and b'="y"])
  next
    case False
    with yne eq_divide_eq[of "y" "- ?Nt x s" "?N c"]
    show ?thesis
      by (simp add: field_simps tmbound0_I[OF lin(3), of vs x bs y] sum_eq[symmetric])
  qed
qed (auto simp: tmbound0_I[where vs=vs and bs="bs" and b="y" and b'="x"]
  bound0_I[where vs=vs and bs="bs" and b="y" and b'="x"])

lemma inf_uset:
  assumes lp: "islin p"
    and nmi: "¬ (Ifm vs (x#bs) (minusinf p))" (is "¬ (Ifm vs (x#bs) (?M p))")
    and npi: "¬ (Ifm vs (x#bs) (plusinf p))" (is "¬ (Ifm vs (x#bs) (?P p))")
    and ex: "∃x. Ifm vs (x#bs) p" (is "∃x. ?I x p")
  shows "∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
    ?I ((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) / 2) p"
proof -
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?N = "Ipoly vs"
  let ?U = "set (uset p)"
  from ex obtain a where pa: "?I a p"
    by blast
  from bound0_I[OF minusinf_nb[OF lp], where bs="bs" and b="x" and b'="a"] nmi
  have nmi': "¬ (?I a (?M p))"
    by simp
  from bound0_I[OF plusinf_nb[OF lp], where bs="bs" and b="x" and b'="a"] npi
  have npi': "¬ (?I a (?P p))"
    by simp
  have "∃(c,t) ∈ set (uset p). ∃(d,s) ∈ set (uset p). ?I ((- ?Nt a t/?N c + - ?Nt a s /?N d) / 2) p"
  proof -
    let ?M = "(λ(c,t). - ?Nt a t / ?N c) ` ?U"
    have fM: "finite ?M"
      by auto
    from minusinf_uset[OF lp nmi pa] plusinf_uset[OF lp npi pa]
    have "∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
        a ≤ - ?Nt x t / ?N c ∧ a ≥ - ?Nt x s / ?N d"
      by blast
    then obtain c t d s
      where ctU: "(c, t) ∈ ?U"
        and dsU: "(d, s) ∈ ?U"
        and xs1: "a ≤ - ?Nt x s / ?N d"
        and tx1: "a ≥ - ?Nt x t / ?N c"
      by blast
    from uset_l[OF lp] ctU dsU tmbound0_I[where bs="bs" and b="x" and b'="a"] xs1 tx1
    have xs: "a ≤ - ?Nt a s / ?N d" and tx: "a ≥ - ?Nt a t / ?N c"
      by auto
    from ctU have Mne: "?M ≠ {}" by auto
    then have Une: "?U ≠ {}" by simp
    let ?l = "Min ?M"
    let ?u = "Max ?M"
    have linM: "?l ∈ ?M"
      using fM Mne by simp
    have uinM: "?u ∈ ?M"
      using fM Mne by simp
    have ctM: "- ?Nt a t / ?N c ∈ ?M"
      using ctU by auto
    have dsM: "- ?Nt a s / ?N d ∈ ?M"
      using dsU by auto
    have lM: "∀t∈ ?M. ?l ≤ t"
      using Mne fM by auto
    have Mu: "∀t∈ ?M. t ≤ ?u"
      using Mne fM by auto
    have "?l ≤ - ?Nt a t / ?N c"
      using ctM Mne by simp
    then have lx: "?l ≤ a"
      using tx by simp
    have "- ?Nt a s / ?N d ≤ ?u"
      using dsM Mne by simp
    then have xu: "a ≤ ?u"
      using xs by simp
    from finite_set_intervals2[where P="λx. ?I x p",OF pa lx xu linM uinM fM lM Mu]
    consider u where "u ∈ ?M" "?I u p"
      | t1 t2 where "t1 ∈ ?M" "t2∈ ?M" "∀y. t1 < y ∧ y < t2 ⟶ y ∉ ?M" "t1 < a" "a < t2" "?I a p"
      by blast
    then show ?thesis
    proof cases
      case 1
      then have "∃(nu,tu) ∈ ?U. u = - ?Nt a tu / ?N nu"
        by auto
      then obtain tu nu where tuU: "(nu, tu) ∈ ?U" and tuu: "u = - ?Nt a tu / ?N nu"
        by blast
      have "?I (((- ?Nt a tu / ?N nu) + (- ?Nt a tu / ?N nu)) / 2) p"
        using ‹?I u p› tuu by simp
      with tuU show ?thesis by blast
    next
      case 2
      have "∃(t1n, t1u) ∈ ?U. t1 = - ?Nt a t1u / ?N t1n"
        using ‹t1 ∈ ?M› by auto
      then obtain t1u t1n where t1uU: "(t1n, t1u) ∈ ?U"
        and t1u: "t1 = - ?Nt a t1u / ?N t1n"
        by blast
      have "∃(t2n, t2u) ∈ ?U. t2 = - ?Nt a t2u / ?N t2n"
        using ‹t2 ∈ ?M› by auto
      then obtain t2u t2n where t2uU: "(t2n, t2u) ∈ ?U"
        and t2u: "t2 = - ?Nt a t2u / ?N t2n"
        by blast
      have "t1 < t2"
        using ‹t1 🚫› ‹a 🚫› by simp
      let ?u = "(t1 + t2) / 2"
      have "t1 < ?u"
        using less_half_sum [OF ‹t1 🚫›] by auto
      have "?u < t2"
        using gt_half_sum [OF ‹t1 🚫›] by auto
      have "?I ?u p"
        using lp ‹∀y. t1 🚫 ∧ y 🚫 ⟶ y ∉ ?M› ‹t1 🚫› ‹a 🚫› ‹?I a p› ‹t1 🚫u› ‹?u 🚫›
        by (rule lin_dense)
      with t1uU t2uU t1u t2u show ?thesis by blast
    qed
  qed
  then obtain l n s  m
    where lnU: "(n, l) ∈ ?U"
      and smU:"(m,s) ∈ ?U"
      and pu: "?I ((- ?Nt a l / ?N n + - ?Nt a s / ?N m) / 2) p"
    by blast
  from lnU smU uset_l[OF lp] have nbl: "tmbound0 l" and nbs: "tmbound0 s"
    by auto
  from tmbound0_I[OF nbl, where bs="bs" and b="a" and b'="x"]
    tmbound0_I[OF nbs, where bs="bs" and b="a" and b'="x"] pu
  have "?I ((- ?Nt x l / ?N n + - ?Nt x s / ?N m) / 2) p"
    by simp
  with lnU smU show ?thesis by auto
qed


section ‹The Ferrante - Rackoff Theorem›

theorem fr_eq:
  assumes lp: "islin p"
  shows "(∃x. Ifm vs (x#bs) p) ⟷
    (Ifm vs (x#bs) (minusinf p) ∨
     Ifm vs (x#bs) (plusinf p) ∨
     (∃(n, t) ∈ set (uset p). ∃(m, s) ∈ set (uset p).
       Ifm vs (((- Itm vs (x#bs) t / Ipoly vs n + - Itm vs (x#bs) s / Ipoly vs m) / 2)#bs) p))"
  (is "(∃x. ?I x p) ⟷ ?M ∨ ?P ∨ ?F" is "?E ⟷ ?D")
proof
  show ?D if ?E
  proof -
    consider "?M ∨ ?P" | "¬ ?M" "¬ ?P" by blast
    then show ?thesis
    proof cases
      case 1
      then show ?thesis by blast
    next
      case 2
      from inf_uset[OF lp this] have ?F
        using ‹?E› by blast
      then show ?thesis by blast
    qed
  qed
  show ?E if ?D
  proof -
    from that consider ?M | ?P | ?F by blast
    then show ?thesis
    proof cases
      case 1
      from minusinf_ex[OF lp this] show ?thesis .
    next
      case 2
      from plusinf_ex[OF lp this] show ?thesis .
    next
      case 3
      then show ?thesis by blast
    qed
  qed
qed


section ‹First implementation : Naive by encoding all case splits locally›

definition "msubsteq c t d s a r =
  evaldjf (case_prod conj)
  [(let cd = c *🪙p d
    in (NEq (CP cd), Eq (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (conj (Eq (CP c)) (NEq (CP d)), Eq (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (NEq (CP c)) (Eq (CP d)), Eq (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (Eq (CP c)) (Eq (CP d)), Eq r)]"

lemma msubsteq_nb:
  assumes lp: "islin (Eq (CNP 0 a r))"
    and t: "tmbound0 t"
    and s: "tmbound0 s"
  shows "bound0 (msubsteq c t d s a r)"
proof -
  have th: "∀x ∈ set
    [(let cd = c *🪙p d
      in (NEq (CP cd), Eq (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
     (conj (Eq (CP c)) (NEq (CP d)), Eq (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
     (conj (NEq (CP c)) (Eq (CP d)), Eq (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
     (conj (Eq (CP c)) (Eq (CP d)), Eq r)]. bound0 (case_prod conj x)"
    using lp by (simp add: Let_def t s)
  from evaldjf_bound0[OF th] show ?thesis
    by (simp add: msubsteq_def)
qed

lemma msubsteq:
  assumes lp: "islin (Eq (CNP 0 a r))"
  shows "Ifm vs (x#bs) (msubsteq c t d s a r) =
    Ifm vs (((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) / 2)#bs) (Eq (CNP 0 a r))"
  (is "?lhs = ?rhs")
proof -
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?N = "λp. Ipoly vs p"
  let ?c = "?N c"
  let ?d = "?N d"
  let ?t = "?Nt x t"
  let ?s = "?Nt x s"
  let ?a = "?N a"
  let ?r = "?Nt x r"
  from lp have lin:"isnpoly a" "a ≠ 0🪙p" "tmbound0 r" "allpolys isnpoly r"
    by simp_all
  note r = tmbound0_I[OF lin(3), of vs _ bs x]
  consider "?c = 0" "?d = 0" | "?c = 0" "?d ≠ 0" | "?c ≠ 0" "?d = 0" | "?c ≠ 0" "?d ≠ 0"
    by blast
  then show ?thesis
  proof cases
    case 1
    then show ?thesis
      by (simp add: r[of 0] msubsteq_def Let_def evaldjf_ex)
  next
    case cd: 2
    then have th: "(- ?t / ?c + - ?s / ?d)/2 = -?s / (2*?d)"
      by simp
    have "?rhs = Ifm vs (-?s / (2*?d) # bs) (Eq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (-?s / (2*?d)) + ?r = 0"
      by (simp add: r[of "- (Itm vs (x # bs) s / (2 * (d)🪙p🪙vs🪙))"])
    also have "… ⟷ 2 * ?d * (?a * (-?s / (2*?d)) + ?r) = 0"
      using cd(2) mult_cancel_left[of "2*?d" "(?a * (-?s / (2*?d)) + ?r)" 0] by simp
    also have "… ⟷ (- ?a * ?s) * (2*?d / (2*?d)) + 2 * ?d * ?r= 0"
      by (simp add: field_simps distrib_left [of "2*?d"])
    also have "… ⟷ - (?a * ?s) + 2*?d*?r = 0"
      using cd(2) by simp
    finally show ?thesis
      using cd
      by (simp add: r[of "- (Itm vs (x # bs) s / (2 * (d)🪙p🪙vs🪙))"] msubsteq_def Let_def evaldjf_ex)
  next
    case cd: 3
    from cd(2) have th: "(- ?t / ?c + - ?s / ?d)/2 = -?t / (2 * ?c)"
      by simp
    have "?rhs = Ifm vs (-?t / (2*?c) # bs) (Eq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (-?t / (2*?c)) + ?r = 0"
      by (simp add: r[of "- (?t/ (2 * ?c))"])
    also have "… ⟷ 2 * ?c * (?a * (-?t / (2 * ?c)) + ?r) = 0"
      using cd(1) mult_cancel_left[of "2 * ?c" "(?a * (-?t / (2 * ?c)) + ?r)" 0] by simp
    also have "… ⟷ (?a * -?t)* (2 * ?c) / (2 * ?c) + 2 * ?c * ?r= 0"
      by (simp add: field_simps distrib_left [of "2 * ?c"])
    also have "… ⟷ - (?a * ?t) + 2 * ?c * ?r = 0"
      using cd(1) by simp
    finally show ?thesis using cd
      by (simp add: r[of "- (?t/ (2 * ?c))"] msubsteq_def Let_def evaldjf_ex)
  next
    case cd: 4
    then have cd2: "?c * ?d * 2 ≠ 0"
      by simp
    from add_frac_eq[OF cd, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c* ?s )/ (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2*?c*?d) # bs) (Eq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r = 0"
      by (simp add: r [of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r) = 0"
      using cd mult_cancel_left[of "2 * ?c * ?d" "?a * (- (?d * ?t + ?c* ?s)/ (2 * ?c * ?d)) + ?r" 0]
      by simp
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )) + 2 * ?c * ?d * ?r = 0"
      using nonzero_mult_div_cancel_left [OF cd2] cd
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"]
          msubsteq_def Let_def evaldjf_ex field_simps)
  qed
qed


definition "msubstneq c t d s a r =
  evaldjf (case_prod conj)
  [(let cd = c *🪙p d
    in (NEq (CP cd), NEq (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (conj (Eq (CP c)) (NEq (CP d)), NEq (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (NEq (CP c)) (Eq (CP d)), NEq (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (Eq (CP c)) (Eq (CP d)), NEq r)]"

lemma msubstneq_nb:
  assumes lp: "islin (NEq (CNP 0 a r))"
    and t: "tmbound0 t"
    and s: "tmbound0 s"
  shows "bound0 (msubstneq c t d s a r)"
proof -
  have th: "∀x∈ set
   [(let cd = c *🪙p d
     in (NEq (CP cd), NEq (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
    (conj (Eq (CP c)) (NEq (CP d)), NEq (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
    (conj (NEq (CP c)) (Eq (CP d)), NEq (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
    (conj (Eq (CP c)) (Eq (CP d)), NEq r)]. bound0 (case_prod conj x)"
    using lp by (simp add: Let_def t s)
  from evaldjf_bound0[OF th] show ?thesis
    by (simp add: msubstneq_def)
qed

lemma msubstneq:
  assumes lp: "islin (Eq (CNP 0 a r))"
  shows "Ifm vs (x#bs) (msubstneq c t d s a r) =
    Ifm vs (((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) /2)#bs) (NEq (CNP 0 a r))"
  (is "?lhs = ?rhs")
proof -
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?N = "λp. Ipoly vs p"
  let ?c = "?N c"
  let ?d = "?N d"
  let ?t = "?Nt x t"
  let ?s = "?Nt x s"
  let ?a = "?N a"
  let ?r = "?Nt x r"
  from lp have lin:"isnpoly a" "a ≠ 0🪙p" "tmbound0 r" "allpolys isnpoly r"
    by simp_all
  note r = tmbound0_I[OF lin(3), of vs _ bs x]
  consider "?c = 0" "?d = 0" | "?c = 0" "?d ≠ 0" | "?c ≠ 0" "?d = 0" | "?c ≠ 0" "?d ≠ 0"
    by blast
  then show ?thesis
  proof cases
    case 1
    then show ?thesis
      by (simp add: r[of 0] msubstneq_def Let_def evaldjf_ex)
  next
    case cd: 2
    from cd(1) have th: "(- ?t / ?c + - ?s / ?d)/2 = -?s / (2 * ?d)"
      by simp
    have "?rhs = Ifm vs (-?s / (2*?d) # bs) (NEq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (-?s / (2*?d)) + ?r ≠ 0"
      by (simp add: r[of "- (Itm vs (x # bs) s / (2 * (d)🪙p🪙vs🪙))"])
    also have "… ⟷ 2*?d * (?a * (-?s / (2*?d)) + ?r) ≠ 0"
      using cd(2) mult_cancel_left[of "2*?d" "(?a * (-?s / (2*?d)) + ?r)" 0] by simp
    also have "… ⟷ (- ?a * ?s) * (2*?d / (2*?d)) + 2*?d*?r≠ 0"
      by (simp add: field_simps distrib_left[of "2*?d"] del: distrib_left)
    also have "… ⟷ - (?a * ?s) + 2*?d*?r ≠ 0"
      using cd(2) by simp
    finally show ?thesis
      using cd
      by (simp add: r[of "- (Itm vs (x # bs) s / (2 * (d)🪙p🪙vs🪙))"] msubstneq_def Let_def evaldjf_ex)
  next
    case cd: 3
    from cd(2) have th: "(- ?t / ?c + - ?s / ?d)/2 = -?t / (2*?c)"
      by simp
    have "?rhs = Ifm vs (-?t / (2*?c) # bs) (NEq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (-?t / (2*?c)) + ?r ≠ 0"
      by (simp add: r[of "- (?t/ (2 * ?c))"])
    also have "… ⟷ 2*?c * (?a * (-?t / (2*?c)) + ?r) ≠ 0"
      using cd(1) mult_cancel_left[of "2*?c" "(?a * (-?t / (2*?c)) + ?r)" 0] by simp
    also have "… ⟷ (?a * -?t)* (2*?c) / (2*?c) + 2*?c*?r ≠ 0"
      by (simp add: field_simps distrib_left[of "2*?c"] del: distrib_left)
    also have "… ⟷ - (?a * ?t) + 2*?c*?r ≠ 0"
      using cd(1) by simp
    finally show ?thesis
      using cd by (simp add: r[of "- (?t/ (2*?c))"] msubstneq_def Let_def evaldjf_ex)
  next
    case cd: 4
    then have cd2: "?c * ?d * 2 ≠ 0"
      by simp
    from add_frac_eq[OF cd, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c * ?s )/ (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2*?c*?d) # bs) (NEq (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r ≠ 0"
      by (simp add: r [of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r) ≠ 0"
      using cd mult_cancel_left[of "2 * ?c * ?d" "?a * (- (?d * ?t + ?c* ?s)/ (2*?c*?d)) + ?r" 0]
      by simp
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )) + 2*?c*?d*?r ≠ 0"
      using nonzero_mult_div_cancel_left[OF cd2] cd
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"]
          msubstneq_def Let_def evaldjf_ex field_simps)
  qed
qed

definition "msubstlt c t d s a r =
  evaldjf (case_prod conj)
  [(let cd = c *🪙p d
    in (lt (CP (~🪙p cd)), Lt (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (let cd = c *🪙p d
    in (lt (CP cd), Lt (Sub (Mul a (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (conj (lt (CP (~🪙p c))) (Eq (CP d)), Lt (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (lt (CP c)) (Eq (CP d)), Lt (Sub (Mul a t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (lt (CP (~🪙p d))) (Eq (CP c)), Lt (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (lt (CP d)) (Eq (CP c)), Lt (Sub (Mul a s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (Eq (CP c)) (Eq (CP d)), Lt r)]"

lemma msubstlt_nb:
  assumes lp: "islin (Lt (CNP 0 a r))"
    and t: "tmbound0 t"
    and s: "tmbound0 s"
  shows "bound0 (msubstlt c t d s a r)"
proof -
  have th: "∀x∈ set
  [(let cd = c *🪙p d
    in (lt (CP (~🪙p cd)), Lt (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (let cd = c *🪙p d
    in (lt (CP cd), Lt (Sub (Mul a (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
   (conj (lt (CP (~🪙p c))) (Eq (CP d)), Lt (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (lt (CP c)) (Eq (CP d)), Lt (Sub (Mul a t) (Mul ((2)🪙p *🪙p c) r))),
   (conj (lt (CP (~🪙p d))) (Eq (CP c)), Lt (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (lt (CP d)) (Eq (CP c)), Lt (Sub (Mul a s) (Mul ((2)🪙p *🪙p d) r))),
   (conj (Eq (CP c)) (Eq (CP d)), Lt r)]. bound0 (case_prod conj x)"
    using lp by (simp add: Let_def t s lt_nb)
  from evaldjf_bound0[OF th] show ?thesis
    by (simp add: msubstlt_def)
qed

lemma msubstlt:
  assumes nc: "isnpoly c"
    and nd: "isnpoly d"
    and lp: "islin (Lt (CNP 0 a r))"
  shows "Ifm vs (x#bs) (msubstlt c t d s a r) ⟷
    Ifm vs (((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) /2)#bs) (Lt (CNP 0 a r))"
  (is "?lhs = ?rhs")
proof -
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?N = "λp. Ipoly vs p"
  let ?c = "?N c"
  let ?d = "?N d"
  let ?t = "?Nt x t"
  let ?s = "?Nt x s"
  let ?a = "?N a"
  let ?r = "?Nt x r"
  from lp have lin:"isnpoly a" "a ≠ 0🪙p" "tmbound0 r" "allpolys isnpoly r"
    by simp_all
  note r = tmbound0_I[OF lin(3), of vs _ bs x]
  consider "?c = 0" "?d = 0" | "?c * ?d > 0" | "?c * ?d < 0"
    | "?c > 0" "?d = 0" | "?c < 0" "?d = 0" | "?c = 0" "?d > 0" | "?c = 0" "?d < 0"
    by atomize_elim auto
  then show ?thesis
  proof cases
    case 1
    then show ?thesis
      using nc nd by (simp add: polyneg_norm lt r[of 0] msubstlt_def Let_def evaldjf_ex)
  next
    case cd: 2
    then have cd2: "2 * ?c * ?d > 0"
      by simp
    from cd have c: "?c ≠ 0" and d: "?d ≠ 0"
      by auto
    from cd2 have cd2': "¬ 2 * ?c * ?d < 0" by simp
    from add_frac_eq[OF c d, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c* ?s )/ (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2*?c*?d) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r < 0"
      by (simp add: r[of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r) < 0"
      using cd2 cd2'
        mult_less_cancel_left_disj[of "2 * ?c * ?d" "?a * (- (?d * ?t + ?c* ?s)/ (2*?c*?d)) + ?r" 0]
      by simp
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )) + 2*?c*?d*?r < 0"
      using nonzero_mult_div_cancel_left[of "2*?c*?d"] c d
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd c d nc nd cd2'
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"]
          msubstlt_def Let_def evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case cd: 3
    then have cd2: "2 * ?c * ?d < 0"
      by (simp add: mult_less_0_iff field_simps)
    from cd have c: "?c ≠ 0" and d: "?d ≠ 0"
      by auto
    from add_frac_eq[OF c d, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c* ?s) / (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2 * ?c * ?d) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2 * ?c * ?d)) + ?r < 0"
      by (simp add: r[of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c * ?s )/ (2 * ?c * ?d)) + ?r) > 0"
      using cd2 order_less_not_sym[OF cd2]
        mult_less_cancel_left_disj[of "2 * ?c * ?d" 0 "?a * (- (?d * ?t + ?c* ?s)/ (2*?c*?d)) + ?r"]
      by simp
    also have "… ⟷ ?a * ((?d * ?t + ?c* ?s )) - 2 * ?c * ?d * ?r < 0"
      using nonzero_mult_div_cancel_left[of "2 * ?c * ?d"] c d
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd c d nc nd
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"]
          msubstlt_def Let_def evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case cd: 4
    from cd(1) have c'': "2 * ?c > 0"
      by (simp add: zero_less_mult_iff)
    from cd(1) have c': "2 * ?c ≠ 0"
      by simp
    from cd(2) have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?t / (2 * ?c)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?t / (2 * ?c) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?t / (2 * ?c))+ ?r < 0"
      by (simp add: r[of "- (?t / (2 * ?c))"])
    also have "… ⟷ 2 * ?c * (?a * (- ?t / (2 * ?c))+ ?r) < 0"
      using cd(1) mult_less_cancel_left_disj[of "2 * ?c" "?a* (- ?t / (2*?c))+ ?r" 0] c' c''
        order_less_not_sym[OF c'']
      by simp
    also have "… ⟷ - ?a * ?t + 2 * ?c * ?r < 0"
      using nonzero_mult_div_cancel_left[OF c'] ‹?c > 0›
      by (simp add: algebra_simps diff_divide_distrib less_le del: distrib_right)
    finally show ?thesis
      using cd nc nd
      by (simp add: r[of "- (?t / (2*?c))"] msubstlt_def Let_def evaldjf_ex field_simps
          lt polyneg_norm polymul_norm)
  next
    case cd: 5
    from cd(1) have c': "2 * ?c ≠ 0"
      by simp
    from cd(1) have c'': "2 * ?c < 0"
      by (simp add: mult_less_0_iff)
    from cd(2) have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?t / (2 * ?c)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?t / (2*?c) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?t / (2*?c))+ ?r < 0"
      by (simp add: r[of "- (?t / (2*?c))"])
    also have "… ⟷ 2 * ?c * (?a * (- ?t / (2 * ?c))+ ?r) > 0"
      using cd(1) order_less_not_sym[OF c''] less_imp_neq[OF c''] c''
        mult_less_cancel_left_disj[of "2 * ?c" 0 "?a* (- ?t / (2*?c))+ ?r"]
      by simp
    also have "… ⟷ ?a*?t - 2*?c *?r < 0"
      using nonzero_mult_div_cancel_left[OF c'] cd(1) order_less_not_sym[OF c'']
          less_imp_neq[OF c''] c''
        by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd nc nd
      by (simp add: r[of "- (?t / (2*?c))"] msubstlt_def Let_def evaldjf_ex field_simps
          lt polyneg_norm polymul_norm)
  next
    case cd: 6
    from cd(2) have d'': "2 * ?d > 0"
      by (simp add: zero_less_mult_iff)
    from cd(2) have d': "2 * ?d ≠ 0"
      by simp
    from cd(1) have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?s / (2 * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?s / (2 * ?d) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?s / (2 * ?d))+ ?r < 0"
      by (simp add: r[of "- (?s / (2 * ?d))"])
    also have "… ⟷ 2 * ?d * (?a * (- ?s / (2 * ?d))+ ?r) < 0"
      using cd(2) mult_less_cancel_left_disj[of "2 * ?d" "?a * (- ?s / (2 * ?d))+ ?r" 0] d' d''
        order_less_not_sym[OF d'']
      by simp
    also have "… ⟷ - ?a * ?s+ 2 * ?d * ?r < 0"
      using nonzero_mult_div_cancel_left[OF d'] cd(2)
      by (simp add: algebra_simps diff_divide_distrib less_le del: distrib_right)
    finally show ?thesis
      using cd nc nd
      by (simp add: r[of "- (?s / (2*?d))"] msubstlt_def Let_def evaldjf_ex field_simps
          lt polyneg_norm polymul_norm)
  next
    case cd: 7
    from cd(2) have d': "2 * ?d ≠ 0"
      by simp
    from cd(2) have d'': "2 * ?d < 0"
      by (simp add: mult_less_0_iff)
    from cd(1) have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?s / (2*?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?s / (2 * ?d) # bs) (Lt (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?s / (2 * ?d)) + ?r < 0"
      by (simp add: r[of "- (?s / (2 * ?d))"])
    also have "… ⟷ 2 * ?d * (?a * (- ?s / (2 * ?d)) + ?r) > 0"
      using cd(2) order_less_not_sym[OF d''] less_imp_neq[OF d''] d''
        mult_less_cancel_left_disj[of "2 * ?d" 0 "?a* (- ?s / (2*?d))+ ?r"]
      by simp
    also have "… ⟷ ?a * ?s - 2 * ?d * ?r < 0"
      using nonzero_mult_div_cancel_left[OF d'] cd(2) order_less_not_sym[OF d'']
          less_imp_neq[OF d''] d''
        by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using cd nc nd
      by (simp add: r[of "- (?s / (2*?d))"] msubstlt_def Let_def evaldjf_ex field_simps
          lt polyneg_norm polymul_norm)
  qed
qed

definition "msubstle c t d s a r =
  evaldjf (case_prod conj)
   [(let cd = c *🪙p d
     in (lt (CP (~🪙p cd)), Le (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
    (let cd = c *🪙p d
     in (lt (CP cd), Le (Sub (Mul a (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
    (conj (lt (CP (~🪙p c))) (Eq (CP d)), Le (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
    (conj (lt (CP c)) (Eq (CP d)), Le (Sub (Mul a t) (Mul ((2)🪙p *🪙p c) r))),
    (conj (lt (CP (~🪙p d))) (Eq (CP c)), Le (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
    (conj (lt (CP d)) (Eq (CP c)), Le (Sub (Mul a s) (Mul ((2)🪙p *🪙p d) r))),
    (conj (Eq (CP c)) (Eq (CP d)), Le r)]"

lemma msubstle_nb:
  assumes lp: "islin (Le (CNP 0 a r))"
    and t: "tmbound0 t"
    and s: "tmbound0 s"
  shows "bound0 (msubstle c t d s a r)"
proof -
  have th: "∀x∈ set
   [(let cd = c *🪙p d
     in (lt (CP (~🪙p cd)), Le (Add (Mul (~🪙p a) (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
    (let cd = c *🪙p d
     in (lt (CP cd), Le (Sub (Mul a (Add (Mul d t) (Mul c s))) (Mul ((2)🪙p *🪙p cd) r)))),
    (conj (lt (CP (~🪙p c))) (Eq (CP d)) , Le (Add (Mul (~🪙p a) t) (Mul ((2)🪙p *🪙p c) r))),
    (conj (lt (CP c)) (Eq (CP d)) , Le (Sub (Mul a t) (Mul ((2)🪙p *🪙p c) r))),
    (conj (lt (CP (~🪙p d))) (Eq (CP c)) , Le (Add (Mul (~🪙p a) s) (Mul ((2)🪙p *🪙p d) r))),
    (conj (lt (CP d)) (Eq (CP c)) , Le (Sub (Mul a s) (Mul ((2)🪙p *🪙p d) r))),
    (conj (Eq (CP c)) (Eq (CP d)) , Le r)]. bound0 (case_prod conj x)"
    using lp by (simp add: Let_def t s lt_nb)
  from evaldjf_bound0[OF th] show ?thesis
    by (simp add: msubstle_def)
qed

lemma msubstle:
  assumes nc: "isnpoly c"
    and nd: "isnpoly d"
    and lp: "islin (Le (CNP 0 a r))"
  shows "Ifm vs (x#bs) (msubstle c t d s a r) ⟷
    Ifm vs (((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) /2)#bs) (Le (CNP 0 a r))"
  (is "?lhs = ?rhs")
proof -
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?N = "λp. Ipoly vs p"
  let ?c = "?N c"
  let ?d = "?N d"
  let ?t = "?Nt x t"
  let ?s = "?Nt x s"
  let ?a = "?N a"
  let ?r = "?Nt x r"
  from lp have lin:"isnpoly a" "a ≠ 0🪙p" "tmbound0 r" "allpolys isnpoly r"
    by simp_all
  note r = tmbound0_I[OF lin(3), of vs _ bs x]
  have "?c * ?d < 0 ∨ ?c * ?d > 0 ∨ (?c = 0 ∧ ?d = 0) ∨ (?c = 0 ∧ ?d < 0) ∨ (?c = 0 ∧ ?d > 0) ∨ (?c < 0 ∧ ?d = 0) ∨ (?c > 0 ∧ ?d = 0)"
    by auto
  then consider "?c = 0" "?d = 0" | "?c * ?d > 0" | "?c * ?d < 0"
    | "?c > 0" "?d = 0" | "?c < 0" "?d = 0" | "?c = 0" "?d > 0" | "?c = 0" "?d < 0"
    by blast
  then show ?thesis
  proof cases
    case 1
    with nc nd show ?thesis
      by (simp add: polyneg_norm polymul_norm lt r[of 0] msubstle_def Let_def evaldjf_ex)
  next
    case dc: 2
    from dc have dc': "2 * ?c * ?d > 0"
      by simp
    then have c: "?c ≠ 0" and d: "?d ≠ 0"
      by auto
    from dc' have dc'': "¬ 2 * ?c * ?d < 0"
      by simp
    from add_frac_eq[OF c d, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c * ?s )/ (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2*?c*?d) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r ≤ 0"
      by (simp add: r[of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r) ≤ 0"
      using dc' dc''
        mult_le_cancel_left[of "2 * ?c * ?d" "?a * (- (?d * ?t + ?c* ?s)/ (2*?c*?d)) + ?r" 0]
      by simp
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )) + 2*?c*?d*?r ≤ 0"
      using nonzero_mult_div_cancel_left[of "2*?c*?d"] c d
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using dc c d  nc nd dc'
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"] msubstle_def
          Let_def evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case dc: 3
    from dc have dc': "2 * ?c * ?d < 0"
      by (simp add: mult_less_0_iff field_simps add_neg_neg add_pos_pos)
    then have c: "?c ≠ 0" and d: "?d ≠ 0"
      by auto
    from add_frac_eq[OF c d, of "- ?t" "- ?s"]
    have th: "(- ?t / ?c + - ?s / ?d)/2 = - (?d * ?t + ?c* ?s )/ (2 * ?c * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- (?d * ?t + ?c* ?s )/ (2*?c*?d) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r ≤ 0"
      by (simp add: r[of "(- (?d * ?t) - (?c *?s)) / (2 * ?c * ?d)"])
    also have "… ⟷ (2 * ?c * ?d) * (?a * (- (?d * ?t + ?c* ?s )/ (2*?c*?d)) + ?r) ≥ 0"
      using dc' order_less_not_sym[OF dc']
        mult_le_cancel_left[of "2 * ?c * ?d" 0 "?a * (- (?d * ?t + ?c* ?s)/ (2*?c*?d)) + ?r"]
      by simp
    also have "… ⟷ ?a * ((?d * ?t + ?c* ?s )) - 2 * ?c * ?d * ?r ≤ 0"
      using nonzero_mult_div_cancel_left[of "2 * ?c * ?d"] c d
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using dc c d  nc nd
      by (simp add: r[of "(- (?d * ?t) + - (?c *?s)) / (2 * ?c * ?d)"] msubstle_def
          Let_def evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case 4
    have c: "?c > 0" and d: "?d = 0" by fact+
    from c have c'': "2 * ?c > 0"
      by (simp add: zero_less_mult_iff)
    from c have c': "2 * ?c ≠ 0"
      by simp
    from d have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?t / (2*?c)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?t / (2 * ?c) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?t / (2 * ?c))+ ?r ≤ 0"
      by (simp add: r[of "- (?t / (2 * ?c))"])
    also have "… ⟷ 2 * ?c * (?a * (- ?t / (2 * ?c))+ ?r) ≤ 0"
      using c mult_le_cancel_left[of "2 * ?c" "?a* (- ?t / (2*?c))+ ?r" 0] c' c''
        order_less_not_sym[OF c'']
      by simp
    also have "… ⟷ - ?a*?t+ 2*?c *?r ≤ 0"
      using nonzero_mult_div_cancel_left[OF c'] c
      by (simp add: algebra_simps diff_divide_distrib less_le del: distrib_right)
    finally show ?thesis
      using c d nc nd
      by (simp add: r[of "- (?t / (2*?c))"] msubstle_def Let_def
          evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case 5
    have c: "?c < 0" and d: "?d = 0" by fact+
    then have c': "2 * ?c ≠ 0"
      by simp
    from c have c'': "2 * ?c < 0"
      by (simp add: mult_less_0_iff)
    from d have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?t / (2*?c)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?t / (2 * ?c) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?t / (2*?c))+ ?r ≤ 0"
      by (simp add: r[of "- (?t / (2*?c))"])
    also have "… ⟷ 2 * ?c * (?a * (- ?t / (2 * ?c))+ ?r) ≥ 0"
      using c order_less_not_sym[OF c''] less_imp_neq[OF c''] c''
        mult_le_cancel_left[of "2 * ?c" 0 "?a* (- ?t / (2*?c))+ ?r"]
      by simp
    also have "… ⟷ ?a * ?t - 2 * ?c * ?r ≤ 0"
      using nonzero_mult_div_cancel_left[OF c'] c order_less_not_sym[OF c'']
          less_imp_neq[OF c''] c''
        by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis using c d nc nd
      by (simp add: r[of "- (?t / (2*?c))"] msubstle_def Let_def
          evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case 6
    have c: "?c = 0" and d: "?d > 0" by fact+
    from d have d'': "2 * ?d > 0"
      by (simp add: zero_less_mult_iff)
    from d have d': "2 * ?d ≠ 0"
      by simp
    from c have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?s / (2 * ?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?s / (2 * ?d) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a * (- ?s / (2 * ?d))+ ?r ≤ 0"
      by (simp add: r[of "- (?s / (2*?d))"])
    also have "… ⟷ 2 * ?d * (?a * (- ?s / (2 * ?d)) + ?r) ≤ 0"
      using d mult_le_cancel_left[of "2 * ?d" "?a* (- ?s / (2*?d))+ ?r" 0] d' d''
        order_less_not_sym[OF d'']
      by simp
    also have "… ⟷ - ?a * ?s + 2 * ?d * ?r ≤ 0"
      using nonzero_mult_div_cancel_left[OF d'] d
      by (simp add: algebra_simps diff_divide_distrib less_le del: distrib_right)
    finally show ?thesis
      using c d nc nd
      by (simp add: r[of "- (?s / (2*?d))"] msubstle_def Let_def
          evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  next
    case 7
    have c: "?c = 0" and d: "?d < 0" by fact+
    then have d': "2 * ?d ≠ 0"
      by simp
    from d have d'': "2 * ?d < 0"
      by (simp add: mult_less_0_iff)
    from c have th: "(- ?t / ?c + - ?s / ?d)/2 = - ?s / (2*?d)"
      by (simp add: field_simps)
    have "?rhs ⟷ Ifm vs (- ?s / (2*?d) # bs) (Le (CNP 0 a r))"
      by (simp only: th)
    also have "… ⟷ ?a* (- ?s / (2*?d))+ ?r ≤ 0"
      by (simp add: r[of "- (?s / (2*?d))"])
    also have "… ⟷ 2*?d * (?a* (- ?s / (2*?d))+ ?r) ≥ 0"
      using d order_less_not_sym[OF d''] less_imp_neq[OF d''] d''
        mult_le_cancel_left[of "2 * ?d" 0 "?a* (- ?s / (2*?d))+ ?r"]
      by simp
    also have "… ⟷ ?a * ?s - 2 * ?d * ?r ≤ 0"
      using nonzero_mult_div_cancel_left[OF d'] d order_less_not_sym[OF d'']
        less_imp_neq[OF d''] d''
      by (simp add: algebra_simps diff_divide_distrib del: distrib_right)
    finally show ?thesis
      using c d nc nd
      by (simp add: r[of "- (?s / (2*?d))"] msubstle_def Let_def
          evaldjf_ex field_simps lt polyneg_norm polymul_norm)
  qed
qed

fun msubst :: "fm ==> (poly × tm) × (poly × tm) ==> fm"
  where
    "msubst (And p q) ((c, t), (d, s)) = conj (msubst p ((c,t),(d,s))) (msubst q ((c, t), (d, s)))"
  | "msubst (Or p q) ((c, t), (d, s)) = disj (msubst p ((c,t),(d,s))) (msubst q ((c, t), (d, s)))"
  | "msubst (Eq (CNP 0 a r)) ((c, t), (d, s)) = msubsteq c t d s a r"
  | "msubst (NEq (CNP 0 a r)) ((c, t), (d, s)) = msubstneq c t d s a r"
  | "msubst (Lt (CNP 0 a r)) ((c, t), (d, s)) = msubstlt c t d s a r"
  | "msubst (Le (CNP 0 a r)) ((c, t), (d, s)) = msubstle c t d s a r"
  | "msubst p ((c, t), (d, s)) = p"

lemma msubst_I:
  assumes lp: "islin p"
    and nc: "isnpoly c"
    and nd: "isnpoly d"
  shows "Ifm vs (x#bs) (msubst p ((c,t),(d,s))) =
    Ifm vs (((- Itm vs (x#bs) t / Ipoly vs c + - Itm vs (x#bs) s / Ipoly vs d) /2)#bs) p"
  using lp
  by (induct p rule: islin.induct)
    (auto simp: tmbound0_I
      [where b = "(- (Itm vs (x # bs) t / (c)🪙p🪙vs🪙) - (Itm vs (x # bs) s / (d)🪙p🪙vs🪙)) / 2"
        and b' = x and bs = bs and vs = vs]
      msubsteq msubstneq msubstlt [OF nc nd] msubstle [OF nc nd])

lemma msubst_nb:
  assumes "islin p"
    and "tmbound0 t"
    and "tmbound0 s"
  shows "bound0 (msubst p ((c,t),(d,s)))"
  using assms
  by (induct p rule: islin.induct) (auto simp: msubsteq_nb msubstneq_nb msubstlt_nb msubstle_nb)

lemma fr_eq_msubst:
  assumes lp: "islin p"
  shows "(∃x. Ifm vs (x#bs) p) ⟷
    (Ifm vs (x#bs) (minusinf p) ∨
     Ifm vs (x#bs) (plusinf p) ∨
     (∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
      Ifm vs (x#bs) (msubst p ((c, t), (d, s)))))"
  (is "(∃x. ?I x p) = (?M ∨ ?P ∨ ?F)" is "?E = ?D")
proof -
  from uset_l[OF lp] have *: "∀(c, s)∈set (uset p). isnpoly c ∧ tmbound0 s"
    by blast
  {
    fix c t d s
    assume ctU: "(c, t) ∈set (uset p)"
      and dsU: "(d,s) ∈set (uset p)"
      and pts: "Ifm vs ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs🪙) / 2 # bs) p"
    from *[rule_format, OF ctU] *[rule_format, OF dsU] have norm:"isnpoly c" "isnpoly d"
      by simp_all
    from msubst_I[OF lp norm, of vs x bs t s] pts
    have "Ifm vs (x # bs) (msubst p ((c, t), d, s))" ..
  }
  moreover
  {
    fix c t d s
    assume ctU: "(c, t) ∈ set (uset p)"
      and dsU: "(d,s) ∈set (uset p)"
      and pts: "Ifm vs (x # bs) (msubst p ((c, t), d, s))"
    from *[rule_format, OF ctU] *[rule_format, OF dsU] have norm:"isnpoly c" "isnpoly d"
      by simp_all
    from msubst_I[OF lp norm, of vs x bs t s] pts
    have "Ifm vs ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs??) / 2 # bs) p" ..
  }
  ultimately have **: "(∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
      Ifm vs ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs🪙) / 2 # bs) p) ⟷ ?F"
    by blast
  from fr_eq[OF lp, of vs bs x, simplified **] show ?thesis .
qed

lemma simpfm_lin:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
  shows "qfree p ==> islin (simpfm p)"
  by (induct p rule: simpfm.induct) (auto simp: conj_lin disj_lin)

definition "ferrack p ≡
  let
    q = simpfm p;
    mp = minusinf q;
    pp = plusinf q
  in
    if (mp = T ∨ pp = T) then T
    else
     (let U = alluopairs (remdups (uset q))
      in decr0 (disj mp (disj pp (evaldjf (simpfm o (msubst q)) U ))))"

lemma ferrack:
  assumes qf: "qfree p"
  shows "qfree (ferrack p) ∧ Ifm vs bs (ferrack p) = Ifm vs bs (E p)"
  (is "_ ∧ ?rhs = ?lhs")
proof -
  let ?I = "λx p. Ifm vs (x#bs) p"
  let ?N = "λt. Ipoly vs t"
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?q = "simpfm p"
  let ?U = "remdups(uset ?q)"
  let ?Up = "alluopairs ?U"
  let ?mp = "minusinf ?q"
  let ?pp = "plusinf ?q"
  fix x
  let ?I = "λp. Ifm vs (x#bs) p"
  from simpfm_lin[OF qf] simpfm_qf[OF qf] have lq: "islin ?q" and q_qf: "qfree ?q" .
  from minusinf_nb[OF lq] plusinf_nb[OF lq] have mp_nb: "bound0 ?mp" and pp_nb: "bound0 ?pp" .
  from bound0_qf[OF mp_nb] bound0_qf[OF pp_nb] have mp_qf: "qfree ?mp" and pp_qf: "qfree ?pp" .
  from uset_l[OF lq] have U_l: "∀(c, s)∈set ?U. isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s"
    by simp
  {
    fix c t d s
    assume ctU: "(c, t) ∈ set ?U"
      and dsU: "(d,s) ∈ set ?U"
    from U_l ctU dsU have norm: "isnpoly c" "isnpoly d"
      by auto
    from msubst_I[OF lq norm, of vs x bs t s] msubst_I[OF lq norm(2,1), of vs x bs s t]
    have "?I (msubst ?q ((c,t),(d,s))) = ?I (msubst ?q ((d,s),(c,t)))"
      by (simp add: field_simps)
  }
  then have th0: "∀x ∈ set ?U. ∀y ∈ set ?U. ?I (msubst ?q (x, y)) ⟷ ?I (msubst ?q (y, x))"
    by auto
  {
    fix x
    assume xUp: "x ∈ set ?Up"
    then obtain c t d s
      where ctU: "(c, t) ∈ set ?U"
        and dsU: "(d,s) ∈ set ?U"
        and x: "x = ((c, t),(d, s))"
      using alluopairs_set1[of ?U] by auto
    from U_l[rule_format, OF ctU] U_l[rule_format, OF dsU]
    have nbs: "tmbound0 t" "tmbound0 s" by simp_all
    from simpfm_bound0[OF msubst_nb[OF lq nbs, of c d]]
    have "bound0 ((simpfm o (msubst (simpfm p))) x)"
      using x by simp
  }
  with evaldjf_bound0[of ?Up "(simpfm o (msubst (simpfm p)))"]
  have "bound0 (evaldjf (simpfm o (msubst (simpfm p))) ?Up)" by blast
  with mp_nb pp_nb
  have th1: "bound0 (disj ?mp (disj ?pp (evaldjf (simpfm o (msubst ?q)) ?Up )))"
    by simp
  from decr0_qf[OF th1] have thqf: "qfree (ferrack p)"
    by (simp add: ferrack_def Let_def)
  have "?lhs ⟷ (∃x. Ifm vs (x#bs) ?q)"
    by simp
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨
      (∃(c, t)∈set ?U. ∃(d, s)∈set ?U. ?I (msubst (simpfm p) ((c, t), d, s)))"
    using fr_eq_msubst[OF lq, of vs bs x] by simp
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨
      (∃(x, y) ∈ set ?Up. ?I ((simpfm ∘ msubst ?q) (x, y)))"
    using alluopairs_bex[OF th0] by simp
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨ ?I (evaldjf (simpfm ∘ msubst ?q) ?Up)"
    by (simp add: evaldjf_ex)
  also have "… ⟷ ?I (disj ?mp (disj ?pp (evaldjf (simpfm ∘ msubst ?q) ?Up)))"
    by simp
  also have "… ⟷ ?rhs"
    using decr0[OF th1, of vs x bs]
    by (cases "?mp = T ∨ ?pp = T") (auto simp: ferrack_def Let_def)
  finally show ?thesis
    using thqf by blast
qed

definition "frpar p = simpfm (qelim p ferrack)"

lemma frpar: "qfree (frpar p) ∧ (Ifm vs bs (frpar p) ⟷ Ifm vs bs p)"
proof -
  from ferrack
  have th: "∀bs p. qfree p ⟶ qfree (ferrack p) ∧ Ifm vs bs (ferrack p) = Ifm vs bs (E p)"
    by blast
  from qelim[OF th, of p bs] show ?thesis
    unfolding frpar_def by auto
qed


section ‹Second implementation: case splits not local›

lemma fr_eq2:
  assumes lp: "islin p"
  shows "(∃x. Ifm vs (x#bs) p) ⟷
   (Ifm vs (x#bs) (minusinf p) ∨
    Ifm vs (x#bs) (plusinf p) ∨
    Ifm vs (0#bs) p ∨
    (∃(n, t) ∈ set (uset p).
      Ipoly vs n ≠ 0 ∧ Ifm vs ((- Itm vs (x#bs) t / (Ipoly vs n * 2))#bs) p) ∨
      (∃(n, t) ∈ set (uset p). ∃(m, s) ∈ set (uset p).
        Ipoly vs n ≠ 0 ∧
        Ipoly vs m ≠ 0 ∧
        Ifm vs (((- Itm vs (x#bs) t / Ipoly vs n + - Itm vs (x#bs) s / Ipoly vs m) /2)#bs) p))"
  (is "(∃x. ?I x p) = (?M ∨ ?P ∨ ?Z ∨ ?U ∨ ?F)" is "?E = ?D")
proof
  assume px: "∃x. ?I x p"
  consider "?M ∨ ?P" | "¬ ?M" "¬ ?P" by blast
  then show ?D
  proof cases
    case 1
    then show ?thesis by blast
  next
    case 2
    have nmi: "¬ ?M" and npi: "¬ ?P" by fact+
    from inf_uset[OF lp nmi npi, OF px]
    obtain c t d s where ct:
      "(c, t) ∈ set (uset p)"
      "(d, s) ∈ set (uset p)"
      "?I ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs🪙) / (1 + 1)) p"
      by auto
    let ?c = "(c)🪙p🪙vs🪙"
    let ?d = "(d)🪙p🪙vs🪙"
    let ?s = "Itm vs (x # bs) s"
    let ?t = "Itm vs (x # bs) t"
    have eq2: "∧(x::'a). x + x = 2 * x"
      by (simp add: field_simps)
    consider "?c = 0" "?d = 0" | "?c = 0" "?d ≠ 0" | "?c ≠ 0" "?d = 0" | "?c ≠ 0" "?d ≠ 0"
      by auto
    then show ?thesis
    proof cases
      case 1
      with ct show ?thesis by simp
    next
      case 2
      with ct show ?thesis by auto
    next
      case 3
      with ct show ?thesis by auto
    next
      case z: 4
      from z have ?F
        using ct
        apply (intro bexI[where x = "(c,t)"]; simp)
        apply (intro bexI[where x = "(d,s)"]; simp)
        done
      then show ?thesis by blast
    qed
  qed
next
  assume ?D
  then consider ?M | ?P | ?Z | ?U | ?F by blast
  then show ?E
  proof cases
    case 1
    show ?thesis by (rule minusinf_ex[OF lp ‹?M›])
  next
    case 2
    show ?thesis by (rule plusinf_ex[OF lp ‹?P›])
  qed blast+
qed

definition "msubsteq2 c t a b = Eq (Add (Mul a t) (Mul c b))"
definition "msubstltpos c t a b = Lt (Add (Mul a t) (Mul c b))"
definition "msubstlepos c t a b = Le (Add (Mul a t) (Mul c b))"
definition "msubstltneg c t a b = Lt (Neg (Add (Mul a t) (Mul c b)))"
definition "msubstleneg c t a b = Le (Neg (Add (Mul a t) (Mul c b)))"

lemma msubsteq2:
  assumes nz: "Ipoly vs c ≠ 0"
    and l: "islin (Eq (CNP 0 a b))"
  shows "Ifm vs (x#bs) (msubsteq2 c t a b) =
    Ifm vs (((Itm vs (x#bs) t / Ipoly vs c ))#bs) (Eq (CNP 0 a b))"
  using nz l tmbound0_I[of b vs x bs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙", symmetric]
  by (simp add: msubsteq2_def field_simps)

lemma msubstltpos:
  assumes nz: "Ipoly vs c > 0"
    and l: "islin (Lt (CNP 0 a b))"
  shows "Ifm vs (x#bs) (msubstltpos c t a b) =
    Ifm vs (((Itm vs (x#bs) t / Ipoly vs c ))#bs) (Lt (CNP 0 a b))"
  using nz l tmbound0_I[of b vs x bs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙", symmetric]
  by (simp add: msubstltpos_def field_simps)

lemma msubstlepos:
  assumes nz: "Ipoly vs c > 0"
    and l: "islin (Le (CNP 0 a b))"
  shows "Ifm vs (x#bs) (msubstlepos c t a b) =
    Ifm vs (((Itm vs (x#bs) t / Ipoly vs c ))#bs) (Le (CNP 0 a b))"
  using nz l tmbound0_I[of b vs x bs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙", symmetric]
  by (simp add: msubstlepos_def field_simps)

lemma msubstltneg:
  assumes nz: "Ipoly vs c < 0"
    and l: "islin (Lt (CNP 0 a b))"
  shows "Ifm vs (x#bs) (msubstltneg c t a b) =
    Ifm vs (((Itm vs (x#bs) t / Ipoly vs c ))#bs) (Lt (CNP 0 a b))"
  using nz l tmbound0_I[of b vs x bs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙", symmetric]
  by (simp add: msubstltneg_def field_simps del: minus_add_distrib)

lemma msubstleneg:
  assumes nz: "Ipoly vs c < 0"
    and l: "islin (Le (CNP 0 a b))"
  shows "Ifm vs (x#bs) (msubstleneg c t a b) =
    Ifm vs (((Itm vs (x#bs) t / Ipoly vs c ))#bs) (Le (CNP 0 a b))"
  using nz l tmbound0_I[of b vs x bs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙", symmetric]
  by (simp add: msubstleneg_def field_simps del: minus_add_distrib)

fun msubstpos :: "fm ==> poly ==> tm ==> fm"
  where
    "msubstpos (And p q) c t = And (msubstpos p c t) (msubstpos q c t)"
  | "msubstpos (Or p q) c t = Or (msubstpos p c t) (msubstpos q c t)"
  | "msubstpos (Eq (CNP 0 a r)) c t = msubsteq2 c t a r"
  | "msubstpos (NEq (CNP 0 a r)) c t = Not (msubsteq2 c t a r)"
  | "msubstpos (Lt (CNP 0 a r)) c t = msubstltpos c t a r"
  | "msubstpos (Le (CNP 0 a r)) c t = msubstlepos c t a r"
  | "msubstpos p c t = p"

lemma msubstpos_I:
  assumes lp: "islin p"
    and pos: "Ipoly vs c > 0"
  shows "Ifm vs (x#bs) (msubstpos p c t) =
    Ifm vs (Itm vs (x#bs) t / Ipoly vs c #bs) p"
  using lp pos
  by (induct p rule: islin.induct)
    (auto simp: msubsteq2 msubstltpos[OF pos] msubstlepos[OF pos]
      tmbound0_I[of _ vs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙" bs x]
      bound0_I[of _ vs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙" bs x] field_simps)

fun msubstneg :: "fm ==> poly ==> tm ==> fm"
  where
    "msubstneg (And p q) c t = And (msubstneg p c t) (msubstneg q c t)"
  | "msubstneg (Or p q) c t = Or (msubstneg p c t) (msubstneg q c t)"
  | "msubstneg (Eq (CNP 0 a r)) c t = msubsteq2 c t a r"
  | "msubstneg (NEq (CNP 0 a r)) c t = Not (msubsteq2 c t a r)"
  | "msubstneg (Lt (CNP 0 a r)) c t = msubstltneg c t a r"
  | "msubstneg (Le (CNP 0 a r)) c t = msubstleneg c t a r"
  | "msubstneg p c t = p"

lemma msubstneg_I:
  assumes lp: "islin p"
    and pos: "Ipoly vs c < 0"
  shows "Ifm vs (x#bs) (msubstneg p c t) = Ifm vs (Itm vs (x#bs) t / Ipoly vs c #bs) p"
  using lp pos
  by (induct p rule: islin.induct)
    (auto simp: msubsteq2 msubstltneg[OF pos] msubstleneg[OF pos]
      tmbound0_I[of _ vs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙" bs x]
      bound0_I[of _ vs "Itm vs (x # bs) t / (c)🪙p🪙vs🪙" bs x] field_simps)

definition "msubst2 p c t =
  disj (conj (lt (CP (polyneg c))) (simpfm (msubstpos p c t)))
    (conj (lt (CP c)) (simpfm (msubstneg p c t)))"

lemma msubst2:
  assumes lp: "islin p"
    and nc: "isnpoly c"
    and nz: "Ipoly vs c ≠ 0"
  shows "Ifm vs (x#bs) (msubst2 p c t) = Ifm vs (Itm vs (x#bs) t / Ipoly vs c #bs) p"
proof -
  let ?c = "Ipoly vs c"
  from nc have anc: "allpolys isnpoly (CP c)" "allpolys isnpoly (CP (~🪙p c))"
    by (simp_all add: polyneg_norm)
  from nz consider "?c < 0" | "?c > 0" by arith
  then show ?thesis
  proof cases
    case c: 1
    from c msubstneg_I[OF lp c, of x bs t] lt[OF anc(1), of vs "x#bs"] lt[OF anc(2), of vs "x#bs"]
    show ?thesis
      by (auto simp: msubst2_def)
  next
    case c: 2
    from c msubstpos_I[OF lp c, of x bs t] lt[OF anc(1), of vs "x#bs"] lt[OF anc(2), of vs "x#bs"]
    show ?thesis
      by (auto simp: msubst2_def)
  qed
qed

lemma msubsteq2_nb: "tmbound0 t ==> islin (Eq (CNP 0 a r)) ==> bound0 (msubsteq2 c t a r)"
  by (simp add: msubsteq2_def)

lemma msubstltpos_nb: "tmbound0 t ==> islin (Lt (CNP 0 a r)) ==> bound0 (msubstltpos c t a r)"
  by (simp add: msubstltpos_def)
lemma msubstltneg_nb: "tmbound0 t ==> islin (Lt (CNP 0 a r)) ==> bound0 (msubstltneg c t a r)"
  by (simp add: msubstltneg_def)

lemma msubstlepos_nb: "tmbound0 t ==> islin (Le (CNP 0 a r)) ==> bound0 (msubstlepos c t a r)"
  by (simp add: msubstlepos_def)
lemma msubstleneg_nb: "tmbound0 t ==> islin (Le (CNP 0 a r)) ==> bound0 (msubstleneg c t a r)"
  by (simp add: msubstleneg_def)

lemma msubstpos_nb:
  assumes lp: "islin p"
    and tnb: "tmbound0 t"
  shows "bound0 (msubstpos p c t)"
  using lp tnb
  by (induct p c t rule: msubstpos.induct)
    (auto simp: msubsteq2_nb msubstltpos_nb msubstlepos_nb)

lemma msubstneg_nb:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
    and lp: "islin p"
    and tnb: "tmbound0 t"
  shows "bound0 (msubstneg p c t)"
  using lp tnb
  by (induct p c t rule: msubstneg.induct)
    (auto simp: msubsteq2_nb msubstltneg_nb msubstleneg_nb)

lemma msubst2_nb:
  assumes "SORT_CONSTRAINT('a::field_char_0)"
    and lp: "islin p"
    and tnb: "tmbound0 t"
  shows "bound0 (msubst2 p c t)"
  using lp tnb
  by (simp add: msubst2_def msubstneg_nb msubstpos_nb lt_nb simpfm_bound0)

lemma mult_minus2_left: "-2 * x = - (2 * x)"
  for x :: "'a::comm_ring_1"
  by simp

lemma mult_minus2_right: "x * -2 = - (x * 2)"
  for x :: "'a::comm_ring_1"
  by simp

lemma islin_qf: "islin p ==> qfree p"
  by (induct p rule: islin.induct) (auto simp: bound0_qf)

lemma fr_eq_msubst2:
  assumes lp: "islin p"
  shows "(∃x. Ifm vs (x#bs) p) ⟷
    ((Ifm vs (x#bs) (minusinf p)) ∨
     (Ifm vs (x#bs) (plusinf p)) ∨
     Ifm vs (x#bs) (subst0 (CP 0🪙p) p) ∨
     (∃(n, t) ∈ set (uset p).
      Ifm vs (x# bs) (msubst2 p (n *🪙p (C (-2,1))) t)) ∨
      (∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
        Ifm vs (x#bs) (msubst2 p (C (-2, 1) *🪙p c*🪙p d) (Add (Mul d t) (Mul c s)))))"
  (is "(∃x. ?I x p) = (?M ∨ ?P ∨ ?Pz ∨ ?PU ∨ ?F)" is "?E = ?D")
proof -
  from uset_l[OF lp] have *: "∀(c, s)∈set (uset p). isnpoly c ∧ tmbound0 s"
    by blast
  let ?I = "λp. Ifm vs (x#bs) p"
  have n2: "isnpoly (C (-2,1))"
    by (simp add: isnpoly_def)
  note eq0 = subst0[OF islin_qf[OF lp], of vs x bs "CP 0🪙p", simplified]

  have eq1: "(∃(n, t) ∈ set (uset p). ?I (msubst2 p (n *🪙p (C (-2,1))) t)) ⟷
    (∃(n, t) ∈ set (uset p).
      (n)🪙p🪙vs🪙 ≠ 0 ∧
      Ifm vs (- Itm vs (x # bs) t / ((n)🪙p🪙vs🪙 * 2) # bs) p)"
  proof -
    {
      fix n t
      assume H: "(n, t) ∈ set (uset p)" "?I(msubst2 p (n *🪙p C (-2, 1)) t)"
      from H(1) * have "isnpoly n"
        by blast
      then have nn: "isnpoly (n *🪙p (C (-2,1)))"
        by (simp_all add: polymul_norm n2)
      have nn': "allpolys isnpoly (CP (~🪙p (n *🪙p C (-2, 1))))"
        by (simp add: polyneg_norm nn)
      then have nn2: "(n *🪙p(C (-2,1)) )🪙p🪙vs🪙 ≠ 0" "(n )🪙p🪙vs🪙 ≠ 0"
        using H(2) nn' nn
        by (auto simp: msubst2_def lt zero_less_mult_iff mult_less_0_iff)
      from msubst2[OF lp nn nn2(1), of x bs t]
      have "(n)🪙p🪙vs🪙 ≠ 0 ∧ Ifm vs (- Itm vs (x # bs) t / ((n)🪙p🪙vs🪙 * 2) # bs) p"
        using H(2) nn2 by (simp add: mult_minus2_right)
    }
    moreover
    {
      fix n t
      assume H:
        "(n, t) ∈ set (uset p)" "(n)🪙p🪙vs🪙 ≠ 0"
        "Ifm vs (- Itm vs (x # bs) t / ((n)🪙p🪙vs🪙 * 2) # bs) p"
      from H(1) * have "isnpoly n"
        by blast
      then have nn: "isnpoly (n *🪙p (C (-2,1)))" "(n *🪙p(C (-2,1)) )🪙p🪙vs🪙 ≠ 0"
        using H(2) by (simp_all add: polymul_norm n2)
      from msubst2[OF lp nn, of x bs t] have "?I (msubst2 p (n *🪙p (C (-2,1))) t)"
        using H(2,3) by (simp add: mult_minus2_right)
    }
    ultimately show ?thesis by blast
  qed
  have eq2: "(∃(c, t) ∈ set (uset p). ∃(d, s) ∈ set (uset p).
      Ifm vs (x#bs) (msubst2 p (C (-2, 1) *🪙p c*🪙p d) (Add (Mul d t) (Mul c s)))) ⟷
    (∃(n, t)∈set (uset p). ∃(m, s)∈set (uset p).
      (n)🪙p🪙vs🪙 ≠ 0 ∧
      (m)🪙p🪙vs🪙 ≠ 0 ∧
      Ifm vs ((- Itm vs (x # bs) t / (n)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (m)🪙p🪙vs🪙) / 2 # bs) p)"
  proof -
    {
      fix c t d s
      assume H:
        "(c,t) ∈ set (uset p)" "(d,s) ∈ set (uset p)"
        "Ifm vs (x#bs) (msubst2 p (C (-2, 1) *🪙p c*🪙p d) (Add (Mul d t) (Mul c s)))"
      from H(1,2) * have "isnpoly c" "isnpoly d"
        by blast+
      then have nn: "isnpoly (C (-2, 1) *🪙p c*🪙p d)"
        by (simp_all add: polymul_norm n2)
      have stupid:
          "allpolys isnpoly (CP (~🪙p (C (-2, 1) *🪙p c *🪙p d)))"
          "allpolys isnpoly (CP ((C (-2, 1) *🪙p c *🪙p d)))"
        by (simp_all add: polyneg_norm nn)
      have nn': "((C (-2, 1) *🪙p c*🪙p d))🪙p🪙vs🪙 ≠ 0" "(c)🪙p🪙vs🪙 ≠ 0" "(d)🪙p🪙vs🪙 ≠ 0"
        using H(3)
        by (auto simp: msubst2_def lt[OF stupid(1)]
            lt[OF stupid(2)] zero_less_mult_iff mult_less_0_iff)
      from msubst2[OF lp nn nn'(1), of x bs ] H(3) nn'
      have "(c)🪙p🪙vs🪙 ≠ 0 ∧ (d)🪙p🪙vs🪙 ≠ 0 ∧
          Ifm vs ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs🪙) / 2 # bs) p"
        by (simp add: add_divide_distrib diff_divide_distrib mult_minus2_left mult.commute)
    }
    moreover
    {
      fix c t d s
      assume H:
        "(c, t) ∈ set (uset p)"
        "(d, s) ∈ set (uset p)"
        "(c)🪙p🪙vs🪙 ≠ 0"
        "(d)🪙p🪙vs🪙 ≠ 0"
        "Ifm vs ((- Itm vs (x # bs) t / (c)🪙p🪙vs🪙 + - Itm vs (x # bs) s / (d)🪙p🪙vs🪙) / 2 # bs) p"
      from H(1,2) * have "isnpoly c" "isnpoly d"
        by blast+
      then have nn: "isnpoly (C (-2, 1) *🪙p c*🪙p d)" "((C (-2, 1) *🪙p c*🪙p d))🪙p🪙vs🪙 ≠ 0"
        using H(3,4) by (simp_all add: polymul_norm n2)
      from msubst2[OF lp nn, of x bs ] H(3,4,5)
      have "Ifm vs (x#bs) (msubst2 p (C (-2, 1) *🪙p c*🪙p d) (Add (Mul d t) (Mul c s)))"
        by (simp add: diff_divide_distrib add_divide_distrib mult_minus2_left mult.commute)
    }
    ultimately show ?thesis by blast
  qed
  from fr_eq2[OF lp, of vs bs x] show ?thesis
    unfolding eq0 eq1 eq2 by blast
qed

definition "ferrack2 p ≡
  let
    q = simpfm p;
    mp = minusinf q;
    pp = plusinf q
  in
    if (mp = T ∨ pp = T) then T
    else
     (let U = remdups (uset q)
      in
        decr0
          (list_disj
            [mp,
             pp,
             simpfm (subst0 (CP 0🪙p) q),
             evaldjf (λ(c, t). msubst2 q (c *🪙p C (-2, 1)) t) U,
             evaldjf (λ((b, a),(d, c)).
              msubst2 q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))) (alluopairs U)]))"

definition "frpar2 p = simpfm (qelim (prep p) ferrack2)"

lemma ferrack2:
  assumes qf: "qfree p"
  shows "qfree (ferrack2 p) ∧ Ifm vs bs (ferrack2 p) = Ifm vs bs (E p)"
    (is "_ ∧ (?rhs = ?lhs)")
proof -
  let ?J = "λx p. Ifm vs (x#bs) p"
  let ?N = "λt. Ipoly vs t"
  let ?Nt = "λx t. Itm vs (x#bs) t"
  let ?q = "simpfm p"
  let ?qz = "subst0 (CP 0🪙p) ?q"
  let ?U = "remdups(uset ?q)"
  let ?Up = "alluopairs ?U"
  let ?mp = "minusinf ?q"
  let ?pp = "plusinf ?q"
  fix x
  let ?I = "λp. Ifm vs (x#bs) p"
  from simpfm_lin[OF qf] simpfm_qf[OF qf] have lq: "islin ?q" and q_qf: "qfree ?q" .
  from minusinf_nb[OF lq] plusinf_nb[OF lq] have mp_nb: "bound0 ?mp" and pp_nb: "bound0 ?pp" .
  from bound0_qf[OF mp_nb] bound0_qf[OF pp_nb] have mp_qf: "qfree ?mp" and pp_qf: "qfree ?pp" .
  from uset_l[OF lq]
  have U_l: "∀(c, s)∈set ?U. isnpoly c ∧ c ≠ 0🪙p ∧ tmbound0 s ∧ allpolys isnpoly s"
    by simp
  have bnd0: "∀x ∈ set ?U. bound0 ((λ(c,t). msubst2 ?q (c *🪙p C (-2, 1)) t) x)"
  proof -
    have "bound0 ((λ(c,t). msubst2 ?q (c *🪙p C (-2, 1)) t) (c,t))"
      if "(c, t) ∈ set ?U" for c t
    proof -
      from U_l that have "tmbound0 t" by blast
      from msubst2_nb[OF lq this] show ?thesis by simp
    qed
    then show ?thesis by auto
  qed
  have bnd1: "∀x ∈ set ?Up. bound0 ((λ((b, a), (d, c)).
    msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))) x)"
  proof -
    have "bound0 ((λ((b, a),(d, c)).
      msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))) ((b,a),(d,c)))"
      if  "((b,a),(d,c)) ∈ set ?Up" for b a d c
    proof -
      from U_l alluopairs_set1[of ?U] that have this: "tmbound0 (Add (Mul d a) (Mul b c))"
        by auto
      from msubst2_nb[OF lq this] show ?thesis
        by simp
    qed
    then show ?thesis by auto
  qed
  have stupid: "bound0 F" by simp
  let ?R =
    "list_disj
     [?mp,
      ?pp,
      simpfm (subst0 (CP 0🪙p) ?q),
      evaldjf (λ(c,t). msubst2 ?q (c *🪙p C (-2, 1)) t) ?U,
      evaldjf (λ((b,a),(d,c)).
        msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))) (alluopairs ?U)]"
  from subst0_nb[of "CP 0🪙p" ?q] q_qf
    evaldjf_bound0[OF bnd1] evaldjf_bound0[OF bnd0] mp_nb pp_nb stupid
  have nb: "bound0 ?R"
    by (simp add: list_disj_def simpfm_bound0)
  let ?s = "λ((b, a),(d, c)). msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))"

  {
    fix b a d c
    assume baU: "(b,a) ∈ set ?U" and dcU: "(d,c) ∈ set ?U"
    from U_l baU dcU have norm: "isnpoly b" "isnpoly d" "isnpoly (C (-2, 1))"
      by auto (simp add: isnpoly_def)
    have norm2: "isnpoly (C (-2, 1) *🪙p b*🪙p d)" "isnpoly (C (-2, 1) *🪙p d*🪙p b)"
      using norm by (simp_all add: polymul_norm)
    have stupid:
        "allpolys isnpoly (CP (C (-2, 1) *🪙p b *🪙p d))"
        "allpolys isnpoly (CP (C (-2, 1) *🪙p d *🪙p b))"
        "allpolys isnpoly (CP (~🪙p(C (-2, 1) *🪙p b *🪙p d)))"
        "allpolys isnpoly (CP (~🪙p(C (-2, 1) *🪙p d*🪙p b)))"
      by (simp_all add: polyneg_norm norm2)
    have "?I (msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))) =
        ?I (msubst2 ?q (C (-2, 1) *🪙p d*🪙p b) (Add (Mul b c) (Mul d a)))"
      (is "?lhs ⟷ ?rhs")
    proof
      assume H: ?lhs
      then have z: "(C (-2, 1) *🪙p b *🪙p d)🪙p🪙vs🪙 ≠ 0" "(C (-2, 1) *🪙p d *🪙p b)🪙p🪙vs?? ≠ 0"
        by (auto simp: msubst2_def lt[OF stupid(3)] lt[OF stupid(1)]
            mult_less_0_iff zero_less_mult_iff)
      from msubst2[OF lq norm2(1) z(1), of x bs] msubst2[OF lq norm2(2) z(2), of x bs] H
      show ?rhs
        by (simp add: field_simps)
    next
      assume H: ?rhs
      then have z: "(C (-2, 1) *🪙p b *🪙p d)🪙p🪙vs🪙 ≠ 0" "(C (-2, 1) *🪙p d *🪙p b)🪙p🪙vs?? ≠ 0"
        by (auto simp: msubst2_def lt[OF stupid(4)] lt[OF stupid(2)]
            mult_less_0_iff zero_less_mult_iff)
      from msubst2[OF lq norm2(1) z(1), of x bs] msubst2[OF lq norm2(2) z(2), of x bs] H
      show ?lhs
        by (simp add: field_simps)
    qed
  }
  then have th0: "∀x ∈ set ?U. ∀y ∈ set ?U. ?I (?s (x, y)) ⟷ ?I (?s (y, x))"
    by auto

  have "?lhs ⟷ (∃x. Ifm vs (x#bs) ?q)"
    by simp
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨ ?I (subst0 (CP 0🪙p) ?q) ∨
      (∃(n, t) ∈ set ?U. ?I (msubst2 ?q (n *🪙p C (-2, 1)) t)) ∨
      (∃(b, a) ∈ set ?U. ∃(d, c) ∈ set ?U.
        ?I (msubst2 ?q (C (-2, 1) *🪙p b*🪙p d) (Add (Mul d a) (Mul b c))))"
    using fr_eq_msubst2[OF lq, of vs bs x] by simp
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨ ?I (subst0 (CP 0🪙p) ?q) ∨
      (∃(n, t) ∈ set ?U. ?I (msubst2 ?q (n *🪙p C (-2, 1)) t)) ∨
      (∃x ∈ set ?U. ∃y ∈set ?U. ?I (?s (x, y)))"
    by (simp add: split_def)
  also have "… ⟷ ?I ?mp ∨ ?I ?pp ∨ ?I (subst0 (CP 0🪙p) ?q) ∨
      (∃(n, t) ∈ set ?U. ?I (msubst2 ?q (n *🪙p C (-2, 1)) t)) ∨
      (∃(x, y) ∈ set ?Up. ?I (?s (x, y)))"
    using alluopairs_bex[OF th0] by simp
  also have "… ⟷ ?I ?R"
    by (simp add: list_disj_def evaldjf_ex split_def)
  also have "… ⟷ ?rhs"
  proof (cases "?mp = T ∨ ?pp = T")
    case True
    then show ?thesis 
      unfolding ferrack2_def
      by (force simp add: ferrack2_def list_disj_def)
  next
    case False
    then show ?thesis 
      by (simp add: ferrack2_def Let_def decr0[OF nb])
  qed
  finally show ?thesis using decr0_qf[OF nb]
    by (simp add: ferrack2_def Let_def)
qed

lemma frpar2: "qfree (frpar2 p) ∧ (Ifm vs bs (frpar2 p) ⟷ Ifm vs bs p)"
proof -
  from ferrack2
  have this: "∀bs p. qfree p ⟶ qfree (ferrack2 p) ∧ Ifm vs bs (ferrack2 p) = Ifm vs bs (E p)"
    by blast
  from qelim[OF this, of "prep p" bs] show ?thesis
    unfolding frpar2_def by (auto simp: prep)
qed

oracle frpar_oracle =
‹
 let
 
 val mk_C = @{code C} o apply2 @{code int_of_integer};
 val mk_poly_Bound = @{code poly.Bound} o @{code nat_of_integer};
 val mk_Bound = @{code Bound} o @{code nat_of_integer};
 
 val dest_num = snd o HOLogic.dest_number;
 
 fun try_dest_num t = SOME ((snd o HOLogic.dest_number) t)
  handle TERM _ => NONE;
 
fun dest_nat (t as \<^Const_>\<open>Suc\<close>) = HOLogic.dest_nat t  (* FIXME !? *)
  | dest_nat t = dest_num t;

fun the_index ts t =
  let
    val k = find_index (fn t' => t aconv t') ts;
  in if k < 0 then raise General.Subscript else k end;

fun num_of_term ps 🍋‹uminus _ for t› = @{code poly.Neg} (num_of_term ps t)
  | num_of_term ps 🍋‹plus _ for a b› = @{code poly.Add} (num_of_term ps a, num_of_term ps b)
  | num_of_term ps 🍋‹minus _ for a b› = @{code poly.Sub} (num_of_term ps a, num_of_term ps b)
  | num_of_term ps 🍋‹times _ for a b› = @{code poly.Mul} (num_of_term ps a, num_of_term ps b)
  | num_of_term ps 🍋‹power _ for a n› =
      @{code poly.Pw} (num_of_term ps a, @{code nat_of_integer} (dest_nat n))
  | num_of_term ps 🍋‹divide _ for a b› = mk_C (dest_num a, dest_num b)
  | num_of_term ps t =
      (case try_dest_num t of
        SOME k => mk_C (k, 1)
      | NONE => mk_poly_Bound (the_index ps t));

fun tm_of_term fs ps 🍋‹uminus _ for t› = @{code Neg} (tm_of_term fs ps t)
  | tm_of_term fs ps 🍋‹plus _ for a b› = @{code Add} (tm_of_term fs ps a, tm_of_term fs ps b)
  | tm_of_term fs ps 🍋‹minus _ for a b› = @{code Sub} (tm_of_term fs ps a, tm_of_term fs ps b)
  | tm_of_term fs ps 🍋‹times _ for a b› = @{code Mul} (num_of_term ps a, tm_of_term fs ps b)
  | tm_of_term fs ps t = (@{code CP} (num_of_term ps t)
      handle TERM _ => mk_Bound (the_index fs t)
        | General.Subscript => mk_Bound (the_index fs t));

fun fm_of_term fs ps 🍋‹True› = @{code T}
  | fm_of_term fs ps 🍋‹False› = @{code F}
  | fm_of_term fs ps 🍋‹HOL.Not for p› = @{code Not} (fm_of_term fs ps p)
  | fm_of_term fs ps 🍋‹HOL.conj for p q› = @{code And} (fm_of_term fs ps p, fm_of_term fs ps q)
  | fm_of_term fs ps 🍋‹HOL.disj for p q› = @{code Or} (fm_of_term fs ps p, fm_of_term fs ps q)
  | fm_of_term fs ps 🍋‹HOL.implies for p q› =
      @{code Imp} (fm_of_term fs ps p, fm_of_term fs ps q)
  | fm_of_term fs ps 🍋‹HOL.eq 🍋‹bool› for p q› =
      @{code Iff} (fm_of_term fs ps p, fm_of_term fs ps q)
  | fm_of_term fs ps 🍋‹HOL.eq _ for p q› =
      @{code Eq} (@{code Sub} (tm_of_term fs ps p, tm_of_term fs ps q))
  | fm_of_term fs ps 🍋‹less _ for p q› =
      @{code Lt} (@{code Sub} (tm_of_term fs ps p, tm_of_term fs ps q))
  | fm_of_term fs ps 🍋‹less_eq _ for p q› =
      @{code Le} (@{code Sub} (tm_of_term fs ps p, tm_of_term fs ps q))
  | fm_of_term fs ps 🍋‹Ex _ for ‹p as Abs _›\› =
      let val (x', p') = Term.dest_abs_global p
      in @{code E} (fm_of_term (Free x' :: fs) ps p') end
  | fm_of_term fs ps 🍋‹All _ for ‹p as Abs _›\› =
      let val (x', p') = Term.dest_abs_global p
      in @{code A} (fm_of_term (Free x' :: fs) ps p') end
  | fm_of_term fs ps _ = error "fm_of_term";

fun term_of_num T ps (@{code poly.C} (a, b)) =
      let
        val (c, d) = apply2 (@{code integer_of_int}) (a, b)
      in
        if d = 1 then HOLogic.mk_number T c
        else if d = 0 then 🍋‹zero_class.zero T›
        else 🍋‹divide T for ‹HOLogic.mk_number T c› ‹HOLogic.mk_number T d›\›
      end
  | term_of_num T ps (@{code poly.Bound} i) = nth ps (@{code integer_of_nat} i)
  | term_of_num T ps (@{code poly.Add} (a, b)) =
      🍋‹plus T for ‹term_of_num T ps a› ‹term_of_num T ps b›\›
  | term_of_num T ps (@{code poly.Mul} (a, b)) =
      🍋‹times T for ‹term_of_num T ps a› ‹term_of_num T ps b›\›
  | term_of_num T ps (@{code poly.Sub} (a, b)) =
      🍋‹minus T for ‹term_of_num T ps a› ‹term_of_num T ps b›\›
  | term_of_num T ps (@{code poly.Neg} a) =
      🍋‹uminus T for ‹term_of_num T ps a›\›
  | term_of_num T ps (@{code poly.Pw} (a, n)) =
      🍋‹power T for ‹term_of_num T ps a› ‹HOLogic.mk_number 🍋‹nat› (@{code integer_of_nat} n)›\›
  | term_of_num T ps (@{code poly.CN} (c, n, p)) =
      term_of_num T ps (@{code poly.Add} (c, @{code poly.Mul} (@{code poly.Bound} n, p)));

fun term_of_tm T fs ps (@{code CP} p) = term_of_num T ps p
  | term_of_tm T fs ps (@{code Bound} i) = nth fs (@{code integer_of_nat} i)
  | term_of_tm T fs ps (@{code Add} (a, b)) =
      🍋‹plus T for ‹term_of_tm T fs ps a› ‹term_of_tm T fs ps b›\›
  | term_of_tm T fs ps (@{code Mul} (a, b)) =
      🍋‹times T for ‹term_of_num T ps a› ‹term_of_tm T fs ps b›\›
  | term_of_tm T fs ps (@{code Sub} (a, b)) =
      🍋‹minus T for ‹term_of_tm T fs ps a› ‹term_of_tm T fs ps b›\›
  | term_of_tm T fs ps (@{code Neg} a) =
      🍋‹uminus T for ‹term_of_tm T fs ps a›\›
  | term_of_tm T fs ps (@{code CNP} (n, c, p)) =
      term_of_tm T fs ps (@{code Add} (@{code Mul} (c, @{code Bound} n), p));

fun term_of_fm T fs ps @{code T} = 🍋‹True›
  | term_of_fm T fs ps @{code F} = 🍋‹False›
  | term_of_fm T fs ps (@{code Not} p) = 🍋‹HOL.Not for ‹term_of_fm T fs ps p›\›
  | term_of_fm T fs ps (@{code And} (p, q)) =
      🍋‹HOL.conj for ‹term_of_fm T fs ps p› ‹term_of_fm T fs ps q›\›
  | term_of_fm T fs ps (@{code Or} (p, q)) =
      🍋‹HOL.disj for ‹term_of_fm T fs ps p› ‹term_of_fm T fs ps q›\›
  | term_of_fm T fs ps (@{code Imp} (p, q)) =
      🍋‹HOL.implies for ‹term_of_fm T fs ps p› ‹term_of_fm T fs ps q›\›
  | term_of_fm T fs ps (@{code Iff} (p, q)) =
      🍋‹HOL.eq 🍋‹bool› for ‹term_of_fm T fs ps p› ‹term_of_fm T fs ps q›\›
  | term_of_fm T fs ps (@{code Lt} p) =
      🍋‹less T for ‹term_of_tm T fs ps p› 🍋‹zero_class.zero T›\›
  | term_of_fm T fs ps (@{code Le} p) =
      🍋‹less_eq T for ‹term_of_tm T fs ps p› 🍋‹zero_class.zero T›\›
  | term_of_fm T fs ps (@{code Eq} p) =
      🍋‹HOL.eq T for ‹term_of_tm T fs ps p› 🍋‹zero_class.zero T›\›
  | term_of_fm T fs ps (@{code NEq} p) =
      🍋‹Not for (* FIXME HOL.Not!? *)
  🍋‹HOL.eq T for ‹term_of_tm T fs ps p› 🍋‹zero_class.zero T›\›\›
  | term_of_fm T fs ps _ = error "term_of_fm: quantifiers";

fun frpar_procedure alternative T ps fm =
  let
    val frpar = if alternative then @{code frpar2} else @{code frpar};
    val fs = subtract (op aconv) (map Free (Term.add_frees fm [])) ps;
    val eval = term_of_fm T fs ps o frpar o fm_of_term fs ps;
    val t = HOLogic.dest_Trueprop fm;
  in HOLogic.mk_Trueprop (HOLogic.mk_eq (t, eval t)) end;

in

  fn (ctxt, alternative, ty, ps, ct) =>
    Thm.cterm_of ctxt
      (frpar_procedure alternative ty ps (Thm.term_of ct))

end
›

ML ‹
 structure Parametric_Ferrante_Rackoff =
 struct
 
 fun tactic ctxt alternative T ps =
  Object_Logic.full_atomize_tac ctxt
  THEN' CSUBGOAL (fn (g, i) =>
  let
  val th = frpar_oracle (ctxt, alternative, T, ps, g);
  in resolve_tac ctxt [th RS iffD2] i end);
 
 fun method alternative =
  let
  fun keyword k = Scan.lift (Args.$$$ k -- Args.colon) >> K ();
  val parsN = "pars";
  val typN = "type";
  val any_keyword = keyword parsN || keyword typN;
  val terms = Scan.repeat (Scan.unless any_keyword Args.term);
  val typ = Scan.unless any_keyword Args.typ;
  in
  (keyword typN |-- typ) -- (keyword parsN |-- terms) >>
  (fn (T, ps) => fn ctxt => SIMPLE_METHOD' (tactic ctxt alternative T ps))
  end;
 
 end;
 ›

method_setup frpar = ‹
  Parametric_Ferrante_Rackoff.method false
 ›

method_setup frpar2 = ‹
  Parametric_Ferrante_Rackoff.method true
 ›

lemma "∃(x::'a::linordered_field). y ≠ -1 ⟶ (y + 1) * x < 0"
  by (metis mult.commute neg_less_0_iff_less nonzero_divide_eq_eq sum_eq zero_less_two)

lemma "∃(x::'a::linordered_field). y ≠ -1 ⟶ (y + 1)*x < 0"
  by (metis mult.right_neutral mult_minus1_right neg_0_le_iff_le nle_le not_less sum_eq)

end