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(* Title: ZF/UNITY/Comp.thy
Author: Sidi O Ehmety, Computer Laboratory
Copyright 1998 University of Cambridge
From Chandy and Sanders, "Reasoning About Program Composition",
Technical Report 2000-003, University of Florida, 2000.
Revised by Sidi Ehmety on January 2001
Added: a strong form of the order relation over component and localize
Theory ported from HOL.
*)
section\<open>Composition\<close>
theory Comp imports Union Increasing begin
definition
component :: "[i,i]=>o" (infixl \<open>component\<close> 65) where
"F component H == (\G. F \ G = H)"
definition
strict_component :: "[i,i]=>o" (infixl \<open>strict'_component\<close> 65) where
"F strict_component H == F component H & F\H"
definition
(* A stronger form of the component relation *)
component_of :: "[i,i]=>o" (infixl \<open>component'_of\<close> 65) where
"F component_of H == (\G. F ok G & F \ G = H)"
definition
strict_component_of :: "[i,i]=>o" (infixl \<open>strict'_component'_of\<close> 65) where
"F strict_component_of H == F component_of H & F\H"
definition
(* Preserves a state function f, in particular a variable *)
preserves :: "(i=>i)=>i" where
"preserves(f) == {F:program. \z. F: stable({s:state. f(s) = z})}"
definition
fun_pair :: "[i=>i, i =>i] =>(i=>i)" where
"fun_pair(f, g) == %x. "
definition
localize :: "[i=>i, i] => i" where
"localize(f,F) == mk_program(Init(F), Acts(F),
AllowedActs(F) \<inter> (\<Union>G\<in>preserves(f). Acts(G)))"
(*** component and strict_component relations ***)
lemma componentI:
"H component F | H component G ==> H component (F \ G)"
apply (unfold component_def, auto)
apply (rule_tac x = "Ga \ G" in exI)
apply (rule_tac [2] x = "G \ F" in exI)
apply (auto simp add: Join_ac)
done
lemma component_eq_subset:
"G \ program ==> (F component G) \
(Init(G) \<subseteq> Init(F) & Acts(F) \<subseteq> Acts(G) & AllowedActs(G) \<subseteq> AllowedActs(F))"
apply (unfold component_def, auto)
apply (rule exI)
apply (rule program_equalityI, auto)
done
lemma component_SKIP [simp]: "F \ program ==> SKIP component F"
apply (unfold component_def)
apply (rule_tac x = F in exI)
apply (force intro: Join_SKIP_left)
done
lemma component_refl [simp]: "F \ program ==> F component F"
apply (unfold component_def)
apply (rule_tac x = F in exI)
apply (force intro: Join_SKIP_right)
done
lemma SKIP_minimal: "F component SKIP ==> programify(F) = SKIP"
apply (rule program_equalityI)
apply (simp_all add: component_eq_subset, blast)
done
lemma component_Join1: "F component (F \ G)"
by (unfold component_def, blast)
lemma component_Join2: "G component (F \ G)"
apply (unfold component_def)
apply (simp (no_asm) add: Join_commute)
apply blast
done
lemma Join_absorb1: "F component G ==> F \ G = G"
by (auto simp add: component_def Join_left_absorb)
lemma Join_absorb2: "G component F ==> F \ G = F"
by (auto simp add: Join_ac component_def)
lemma JOIN_component_iff:
"H \ program==>(JOIN(I,F) component H) \ (\i \ I. F(i) component H)"
apply (case_tac "I=0", force)
apply (simp (no_asm_simp) add: component_eq_subset)
apply auto
apply blast
apply (rename_tac "y")
apply (drule_tac c = y and A = "AllowedActs (H)" in subsetD)
apply (blast elim!: not_emptyE)+
done
lemma component_JOIN: "i \ I ==> F(i) component (\i \ I. (F(i)))"
apply (unfold component_def)
apply (blast intro: JOIN_absorb)
done
lemma component_trans: "[| F component G; G component H |] ==> F component H"
apply (unfold component_def)
apply (blast intro: Join_assoc [symmetric])
done
lemma component_antisym:
"[| F \ program; G \ program |] ==>(F component G & G component F) \ F = G"
apply (simp (no_asm_simp) add: component_eq_subset)
apply clarify
apply (rule program_equalityI, auto)
done
lemma Join_component_iff:
"H \ program ==>
((F \<squnion> G) component H) \<longleftrightarrow> (F component H & G component H)"
apply (simp (no_asm_simp) add: component_eq_subset)
apply blast
done
lemma component_constrains:
"[| F component G; G \ A co B; F \ program |] ==> F \ A co B"
apply (frule constrainsD2)
apply (auto simp add: constrains_def component_eq_subset)
done
(*** preserves ***)
lemma preserves_is_safety_prop [simp]: "safety_prop(preserves(f))"
apply (unfold preserves_def safety_prop_def)
apply (auto dest: ActsD simp add: stable_def constrains_def)
apply (drule_tac c = act in subsetD, auto)
done
lemma preservesI [rule_format]:
"\z. F \ stable({s \ state. f(s) = z}) ==> F \ preserves(f)"
apply (auto simp add: preserves_def)
apply (blast dest: stableD2)
done
lemma preserves_imp_eq:
"[| F \ preserves(f); act \ Acts(F); \ act |] ==> f(s) = f(t)"
apply (unfold preserves_def stable_def constrains_def)
apply (subgoal_tac "s \ state & t \ state")
prefer 2 apply (blast dest!: Acts_type [THEN subsetD], force)
done
lemma Join_preserves [iff]:
"(F \ G \ preserves(v)) \
(programify(F) \<in> preserves(v) & programify(G) \<in> preserves(v))"
by (auto simp add: preserves_def INT_iff)
lemma JOIN_preserves [iff]:
"(JOIN(I,F): preserves(v)) \ (\i \ I. programify(F(i)):preserves(v))"
by (auto simp add: JOIN_stable preserves_def INT_iff)
lemma SKIP_preserves [iff]: "SKIP \ preserves(v)"
by (auto simp add: preserves_def INT_iff)
lemma fun_pair_apply [simp]: "fun_pair(f,g,x) = "
apply (unfold fun_pair_def)
apply (simp (no_asm))
done
lemma preserves_fun_pair:
"preserves(fun_pair(v,w)) = preserves(v) \ preserves(w)"
apply (rule equalityI)
apply (auto simp add: preserves_def stable_def constrains_def, blast+)
done
lemma preserves_fun_pair_iff [iff]:
"F \ preserves(fun_pair(v, w)) \ F \ preserves(v) \ preserves(w)"
by (simp add: preserves_fun_pair)
lemma fun_pair_comp_distrib:
"(fun_pair(f, g) comp h)(x) = fun_pair(f comp h, g comp h, x)"
by (simp add: fun_pair_def metacomp_def)
lemma comp_apply [simp]: "(f comp g)(x) = f(g(x))"
by (simp add: metacomp_def)
lemma preserves_type: "preserves(v)<=program"
by (unfold preserves_def, auto)
lemma preserves_into_program [TC]: "F \ preserves(f) ==> F \ program"
by (blast intro: preserves_type [THEN subsetD])
lemma subset_preserves_comp: "preserves(f) \ preserves(g comp f)"
apply (auto simp add: preserves_def stable_def constrains_def)
apply (drule_tac x = "f (xb)" in spec)
apply (drule_tac x = act in bspec, auto)
done
lemma imp_preserves_comp: "F \ preserves(f) ==> F \ preserves(g comp f)"
by (blast intro: subset_preserves_comp [THEN subsetD])
lemma preserves_subset_stable: "preserves(f) \ stable({s \ state. P(f(s))})"
apply (auto simp add: preserves_def stable_def constrains_def)
apply (rename_tac s' s)
apply (subgoal_tac "f (s) = f (s') ")
apply (force+)
done
lemma preserves_imp_stable:
"F \ preserves(f) ==> F \ stable({s \ state. P(f(s))})"
by (blast intro: preserves_subset_stable [THEN subsetD])
lemma preserves_imp_increasing:
"[| F \ preserves(f); \x \ state. f(x):A |] ==> F \ Increasing.increasing(A, r, f)"
apply (unfold Increasing.increasing_def)
apply (auto intro: preserves_into_program)
apply (rule_tac P = "%x. :r" in preserves_imp_stable, auto)
done
lemma preserves_id_subset_stable:
"st_set(A) ==> preserves(%x. x) \ stable(A)"
apply (unfold preserves_def stable_def constrains_def, auto)
apply (drule_tac x = xb in spec)
apply (drule_tac x = act in bspec)
apply (auto dest: ActsD)
done
lemma preserves_id_imp_stable:
"[| F \ preserves(%x. x); st_set(A) |] ==> F \ stable(A)"
by (blast intro: preserves_id_subset_stable [THEN subsetD])
(** Added by Sidi **)
(** component_of **)
(* component_of is stronger than component *)
lemma component_of_imp_component:
"F component_of H ==> F component H"
apply (unfold component_def component_of_def, blast)
done
(* component_of satisfies many of component's properties *)
lemma component_of_refl [simp]: "F \ program ==> F component_of F"
apply (unfold component_of_def)
apply (rule_tac x = SKIP in exI, auto)
done
lemma component_of_SKIP [simp]: "F \ program ==>SKIP component_of F"
apply (unfold component_of_def, auto)
apply (rule_tac x = F in exI, auto)
done
lemma component_of_trans:
"[| F component_of G; G component_of H |] ==> F component_of H"
apply (unfold component_of_def)
apply (blast intro: Join_assoc [symmetric])
done
(** localize **)
lemma localize_Init_eq [simp]: "Init(localize(v,F)) = Init(F)"
by (unfold localize_def, simp)
lemma localize_Acts_eq [simp]: "Acts(localize(v,F)) = Acts(F)"
by (unfold localize_def, simp)
lemma localize_AllowedActs_eq [simp]:
"AllowedActs(localize(v,F)) = AllowedActs(F) \ (\G \ preserves(v). Acts(G))"
apply (unfold localize_def)
apply (rule equalityI)
apply (auto dest: Acts_type [THEN subsetD])
done
(** Theorems used in ClientImpl **)
lemma stable_localTo_stable2:
"[| F \ stable({s \ state. P(f(s), g(s))}); G \ preserves(f); G \ preserves(g) |]
==> F \<squnion> G \<in> stable({s \<in> state. P(f(s), g(s))})"
apply (auto dest: ActsD preserves_into_program simp add: stable_def constrains_def)
apply (case_tac "act \ Acts (F) ")
apply auto
apply (drule preserves_imp_eq)
apply (drule_tac [3] preserves_imp_eq, auto)
done
lemma Increasing_preserves_Stable:
"[| F \ stable({s \ state. :r}); G \ preserves(f);
F \<squnion> G \<in> Increasing(A, r, g);
\<forall>x \<in> state. f(x):A & g(x):A |]
==> F \<squnion> G \<in> Stable({s \<in> state. <f(s), g(s)>:r})"
apply (auto simp add: stable_def Stable_def Increasing_def Constrains_def all_conj_distrib)
apply (simp_all add: constrains_type [THEN subsetD] preserves_type [THEN subsetD])
apply (blast intro: constrains_weaken)
(*The G case remains*)
apply (auto dest: ActsD simp add: preserves_def stable_def constrains_def ball_conj_distrib all_conj_distrib)
(*We have a G-action, so delete assumptions about F-actions*)
apply (erule_tac V = "\act \ Acts (F). P (act)" for P in thin_rl)
apply (erule_tac V = "\k\A. \act \ Acts (F) . P (k,act)" for P in thin_rl)
apply (subgoal_tac "f (x) = f (xa) ")
apply (auto dest!: bspec)
done
(** Lemma used in AllocImpl **)
lemma Constrains_UN_left:
"[| \x \ I. F \ A(x) Co B; F \ program |] ==> F:(\x \ I. A(x)) Co B"
by (unfold Constrains_def constrains_def, auto)
lemma stable_Join_Stable:
"[| F \ stable({s \ state. P(f(s), g(s))});
\<forall>k \<in> A. F \<squnion> G \<in> Stable({s \<in> state. P(k, g(s))});
G \<in> preserves(f); \<forall>s \<in> state. f(s):A|]
==> F \<squnion> G \<in> Stable({s \<in> state. P(f(s), g(s))})"
apply (unfold stable_def Stable_def preserves_def)
apply (rule_tac A = "(\k \ A. {s \ state. f(s)=k} \ {s \ state. P (f (s), g (s))})" in Constrains_weaken_L)
prefer 2 apply blast
apply (rule Constrains_UN_left, auto)
apply (rule_tac A = "{s \ state. f(s)=k} \ {s \ state. P (f (s), g (s))} \ {s \ state. P (k, g (s))}" and A' = "({s \ state. f(s)=k} \ {s \ state. P (f (s), g (s))}) \ {s \ state. P (k, g (s))}" in Constrains_weaken)
prefer 2 apply blast
prefer 2 apply blast
apply (rule Constrains_Int)
apply (rule constrains_imp_Constrains)
apply (auto simp add: constrains_type [THEN subsetD])
apply (blast intro: constrains_weaken)
apply (drule_tac x = k in spec)
apply (blast intro: constrains_weaken)
done
end
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