(*  Title:      Sequents/S43.thy
    Author:     Martin Coen
    Copyright   1991  University of Cambridge

This implements Rajeev Gore's sequent calculus for S43.
*)

theory S43
imports Modal0
begin

consts
  S43pi :: "[seq'→seq', seq'→seq', seq'→seq',
             seq'→seq', seq'→seq', seq'→seq'] → prop"
syntax
  "_S43pi" :: "[seq, seq, seq, seq, seq, seq] → prop"
                         (‹S43pi((_);(_);(_);(_);(_);(_))› [] 5)

parse_translation ‹
 let
 val tr = seq_tr;
 fun s43pi_tr [s1, s2, s3, s4, s5, s6] =
 Syntax.const const_syntax‹S43pi› $ tr s1 $ tr s2 $ tr s3 $ tr s4 $ tr s5 $ tr s6;
 in [(syntax_const‹_S43pi›, K s43pi_tr)] end
 ›

print_translation ‹
 
 val tr' = seq_tr';
 fun s43pi_tr' [s1, s2, s3, s4, s5, s6] =
 Syntax.const syntax_const‹_S43pi› $ tr' s1 $ tr' s2 $ tr' s3 $ tr' s4 $ tr' s5 $ tr' s6;
  [(const_syntax‹S43pi›, K s43pi_tr')] end
 ›

axiomatization where
(* Definition of the star operation using a set of Horn clauses  *)
(* For system S43: gamma * == {[]P | []P : gamma}                *)
(*                 delta * == {<>P | <>P : delta}                *)

  lstar0:         "|L>" and
  lstar1:         "$G |L> $H ==> []P, $G |L> []P, $H" and
  lstar2:         "$G |L> $H ==> P, $G |L> $H" and
  rstar0:         "|R>" and
  rstar1:         "$G |R> $H ==> <>P, $G |R> <>P, $H" and
  rstar2:         "$G |R> $H ==> P, $G |R> $H" and

(* Set of Horn clauses to generate the antecedents for the S43 pi rule       *)
(* ie                                                                        *)
(*           S1...Sk,Sk+1...Sk+m                                             *)
(*     ----------------------------------                                    *)
(*     <>P1...<>Pk, $G \<turnstile> $H, []Q1...[]Qm                                    *)
(*                                                                           *)
(*  where Si == <>P1...<>Pi-1,<>Pi+1,..<>Pk,Pi, $G * \<turnstile> $H *, []Q1...[]Qm    *)
(*    and Sj == <>P1...<>Pk, $G * \<turnstile> $H *, []Q1...[]Qj-1,[]Qj+1...[]Qm,Qj    *)
(*    and 1<=i<=k and k<j<=k+m                                               *)

  S43pi0:         "S43pi $L;; $R;; $Lbox; $Rdia" and
  S43pi1:
   "[(S43pi <>P,$L'; $L;; $R; $Lbox;$Rdia); $L',P,$L,$Lbox ⊨ $R,$Rdia] ==>
       S43pi $L'; <>P,$L;; $R; $Lbox;$Rdia" and
  S43pi2:
   "[(S43pi $L';; []P,$R'; $R; $Lbox;$Rdia); $L',$Lbox ⊨ $R',P,$R,$Rdia] ==>
       S43pi $L';; $R'; []P,$R; $Lbox;$Rdia" and

(* Rules for [] and <> for S43 *)

  boxL:           "$E, P, $F, []P ⊨ $G ==> $E, []P, $F ⊨ $G" and
  diaR:           "$E ⊨ $F, P, $G, <>P ==> $E ⊨ $F, <>P, $G" and
  pi1:
   "[$L1,<>P,$L2 |L> $Lbox; $L1,<>P,$L2 |R> $Ldia; $R |L> $Rbox; $R |R> $Rdia;
      S43pi ; $Ldia;; $Rbox; $Lbox; $Rdia] ==>
   $L1, <>P, $L2 ⊨ $R" and
  pi2:
   "[$L |L> $Lbox; $L |R> $Ldia; $R1,[]P,$R2 |L> $Rbox; $R1,[]P,$R2 |R> $Rdia;
      S43pi ; $Ldia;; $Rbox; $Lbox; $Rdia] ==>
   $L ⊨ $R1, []P, $R2"


ML ‹
  S43_Prover = Modal_ProverFun
 
 val rewrite_rls = @{thms rewrite_rls}
 val safe_rls = @{thms safe_rls}
 val unsafe_rls = @{thms unsafe_rls} @ [@{thm pi1}, @{thm pi2}]
 val bound_rls = @{thms bound_rls} @ [@{thm boxL}, @{thm diaR}]
 val aside_rls = [@{thm lstar0}, @{thm lstar1}, @{thm lstar2}, @{thm rstar0},
 @{thm rstar1}, @{thm rstar2}, @{thm S43pi0}, @{thm S43pi1}, @{thm S43pi2}]
 
 ›


method_setup S43_solve = ‹
 Scan.succeed (fn ctxt => SIMPLE_METHOD
 (S43_Prover.solve_tac ctxt 2 ORELSE S43_Prover.solve_tac ctxt 3))
 ›


(* Theorems of system T from Hughes and Cresswell and Hailpern, LNCS 129 *)

lemma "⊨ []P ⟶ P" by S43_solve
lemma "⊨ [](P ⟶ Q) ⟶ ([]P ⟶ []Q)" by S43_solve   (* normality*)
lemma "⊨ (P--<Q) ⟶ []P ⟶ []Q" by S43_solve
lemma "⊨ P ⟶ <>P" by S43_solve

lemma "⊨ [](P ∧ Q) ⟷ []P ∧ []Q" by S43_solve
lemma "⊨ <>(P ∨ Q) ⟷ <>P ∨ <>Q" by S43_solve
lemma "⊨ [](P ⟷ Q) ⟷ (P>-<Q)" by S43_solve
lemma "⊨ <>(P ⟶ Q) ⟷ ([]P ⟶ <>Q)" by S43_solve
lemma "⊨ []P ⟷ ¬ <>(¬ P)" by S43_solve
lemma "⊨ [](¬P) ⟷ ¬ <>P" by S43_solve
lemma "⊨ ¬ []P ⟷ <>(¬ P)" by S43_solve
lemma "⊨ [][]P ⟷ ¬ <><>(¬ P)" by S43_solve
lemma "⊨ ¬ <>(P ∨ Q) ⟷ ¬ <>P ∧ ¬ <>Q" by S43_solve

lemma "⊨ []P ∨ []Q ⟶ [](P ∨ Q)" by S43_solve
lemma "⊨ <>(P ∧ Q) ⟶ <>P ∧ <>Q" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ []P ∨ <>Q" by S43_solve
lemma "⊨ <>P ∧ []Q ⟶ <>(P ∧ Q)" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ <>P ∨ []Q" by S43_solve
lemma "⊨ <>(P ⟶ (Q ∧ R)) ⟶ ([]P ⟶ <>Q) ∧ ([]P ⟶ <>R)" by S43_solve
lemma "⊨ (P --< Q) ∧ (Q --<R ) ⟶ (P --< R)" by S43_solve
lemma "⊨ []P ⟶ <>Q ⟶ <>(P ∧ Q)" by S43_solve


(* Theorems of system S4 from Hughes and Cresswell, p.46 *)

lemma "⊨ []A ⟶ A" by S43_solve             (* refexivity *)
lemma "⊨ []A ⟶ [][]A" by S43_solve         (* transitivity *)
lemma "⊨ []A ⟶ <>A" by S43_solve           (* seriality *)
lemma "⊨ <>[](<>A ⟶ []<>A)" by S43_solve
lemma "⊨ <>[](<>[]A ⟶ []A)" by S43_solve
lemma "⊨ []P ⟷ [][]P" by S43_solve
lemma "⊨ <>P ⟷ <><>P" by S43_solve
lemma "⊨ <>[]<>P ⟶ <>P" by S43_solve
lemma "⊨ []<>P ⟷ []<>[]<>P" by S43_solve
lemma "⊨ <>[]P ⟷ <>[]<>[]P" by S43_solve

(* Theorems for system S4 from Hughes and Cresswell, p.60 *)

lemma "⊨ []P ∨ []Q ⟷ []([]P ∨ []Q)" by S43_solve
lemma "⊨ ((P >-< Q) --< R) ⟶ ((P >-< Q) --< []R)" by S43_solve

(* These are from Hailpern, LNCS 129 *)

lemma "⊨ [](P ∧ Q) ⟷ []P ∧ []Q" by S43_solve
lemma "⊨ <>(P ∨ Q) ⟷ <>P ∨ <>Q" by S43_solve
lemma "⊨ <>(P ⟶ Q) ⟷ ([]P ⟶ <>Q)" by S43_solve

lemma "⊨ [](P ⟶ Q) ⟶ (<>P ⟶ <>Q)" by S43_solve
lemma "⊨ []P ⟶ []<>P" by S43_solve
lemma "⊨ <>[]P ⟶ <>P" by S43_solve

lemma "⊨ []P ∨ []Q ⟶ [](P ∨ Q)" by S43_solve
lemma "⊨ <>(P ∧ Q) ⟶ <>P ∧ <>Q" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ []P ∨ <>Q" by S43_solve
lemma "⊨ <>P ∧ []Q ⟶ <>(P ∧ Q)" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ <>P ∨ []Q" by S43_solve


(* Theorems of system S43 *)

lemma "⊨ <>[]P ⟶ []<>P" by S43_solve
lemma "⊨ <>[]P ⟶ [][]<>P" by S43_solve
lemma "⊨ [](<>P ∨ <>Q) ⟶ []<>P ∨ []<>Q" by S43_solve
lemma "⊨ <>[]P ∧ <>[]Q ⟶ <>([]P ∧ []Q)" by S43_solve
lemma "⊨ []([]P ⟶ []Q) ∨ []([]Q ⟶ []P)" by S43_solve
lemma "⊨ [](<>P ⟶ <>Q) ∨ [](<>Q ⟶ <>P)" by S43_solve
lemma "⊨ []([]P ⟶ Q) ∨ []([]Q ⟶ P)" by S43_solve
lemma "⊨ [](P ⟶ <>Q) ∨ [](Q ⟶ <>P)" by S43_solve
lemma "⊨ [](P ⟶ []Q ⟶ R) ∨ [](P ∨ ([]R ⟶ Q))" by S43_solve
lemma "⊨ [](P ∨ (Q ⟶ <>C)) ∨ [](P ⟶ C ⟶ <>Q)" by S43_solve
lemma "⊨ []([]P ∨ Q) ∧ [](P ∨ []Q) ⟶ []P ∨ []Q" by S43_solve
lemma "⊨ <>P ∧ <>Q ⟶ <>(<>P ∧ Q) ∨ <>(P ∧ <>Q)" by S43_solve
lemma "⊨ [](P ∨ Q) ∧ []([]P ∨ Q) ∧ [](P ∨ []Q) ⟶ []P ∨ []Q" by S43_solve
lemma "⊨ <>P ∧ <>Q ⟶ <>(P ∧ Q) ∨ <>(<>P ∧ Q) ∨ <>(P ∧ <>Q)" by S43_solve
lemma "⊨ <>[]<>P ⟷ []<>P" by S43_solve
lemma "⊨ []<>[]P ⟷ <>[]P" by S43_solve

(* These are from Hailpern, LNCS 129 *)

lemma "⊨ [](P ∧ Q) ⟷ []P ∧ []Q" by S43_solve
lemma "⊨ <>(P ∨ Q) ⟷ <>P ∨ <>Q" by S43_solve
lemma "⊨ <>(P ⟶ Q) ⟷ []P ⟶ <>Q" by S43_solve

lemma "⊨ [](P ⟶ Q) ⟶ <>P ⟶ <>Q" by S43_solve
lemma "⊨ []P ⟶ []<>P" by S43_solve
lemma "⊨ <>[]P ⟶ <>P" by S43_solve
lemma "⊨ []<>[]P ⟶ []<>P" by S43_solve
lemma "⊨ <>[]P ⟶ <>[]<>P" by S43_solve
lemma "⊨ <>[]P ⟶ []<>P" by S43_solve
lemma "⊨ []<>[]P ⟷ <>[]P" by S43_solve
lemma "⊨ <>[]<>P ⟷ []<>P" by S43_solve

lemma "⊨ []P ∨ []Q ⟶ [](P ∨ Q)" by S43_solve
lemma "⊨ <>(P ∧ Q) ⟶ <>P ∧ <>Q" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ []P ∨ <>Q" by S43_solve
lemma "⊨ <>P ∧ []Q ⟶ <>(P ∧ Q)" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ <>P ∨ []Q" by S43_solve
lemma "⊨ [](P ∨ Q) ⟶ []<>P ∨ []<>Q" by S43_solve
lemma "⊨ <>[]P ∧ <>[]Q ⟶ <>(P ∧ Q)" by S43_solve
lemma "⊨ <>[](P ∧ Q) ⟷ <>[]P ∧ <>[]Q" by S43_solve
lemma "⊨ []<>(P ∨ Q) ⟷ []<>P ∨ []<>Q" by S43_solve

end