(*  Title:      HOL/UNITY/Union.ML

    ID:         $Id$

    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory

    Copyright   1998  University of Cambridge

Unions of programs

From Misra's Chapter 5: Asynchronous Compositions of Programs

*)

Addcongs [UN_cong, INT_cong];

(** SKIP **)

Goal "Init SKIP = UNIV";

by (simp_tac (simpset() addsimps [SKIP_def]) 1);

qed "Init_SKIP";

Goal "Acts SKIP = {Id}";

by (simp_tac (simpset() addsimps [SKIP_def]) 1);

qed "Acts_SKIP";

Addsimps [Init_SKIP, Acts_SKIP];

Goal "reachable SKIP = UNIV";

by (force_tac (claset() addEs [reachable.induct]

			addIs reachable.intrs, simpset()) 1);

qed "reachable_SKIP";

Addsimps [reachable_SKIP];

(** SKIP and safety properties **)

Goalw [constrains_def] "(SKIP : A co B) = (A<=B)";

by Auto_tac;

qed "SKIP_in_constrains_iff";

AddIffs [SKIP_in_constrains_iff];

Goalw [Constrains_def] "(SKIP : A Co B) = (A<=B)";

by Auto_tac;

qed "SKIP_in_Constrains_iff";

AddIffs [SKIP_in_Constrains_iff];

Goalw [stable_def] "SKIP : stable A";

by Auto_tac;

qed "SKIP_in_stable";

AddIffs [SKIP_in_stable, SKIP_in_stable RS stable_imp_Stable];

(** Join **)

Goal "Init (F Join G) = Init F Int Init G";

by (simp_tac (simpset() addsimps [Join_def]) 1);

qed "Init_Join";

Goal "Acts (F Join G) = Acts F Un Acts G";

by (auto_tac (claset(), simpset() addsimps [Join_def]));

qed "Acts_Join";

Addsimps [Init_Join, Acts_Join];

(** JN **)

Goalw [JOIN_def, SKIP_def] "(JN i:{}. F i) = SKIP";

by Auto_tac;

qed "JN_empty";

Addsimps [JN_empty];

Goal "(JN i:insert a I. F i) = (F a) Join (JN i:I. F i)";

by (rtac program_equalityI 1);

by (ALLGOALS (simp_tac (simpset() addsimps [JOIN_def, Join_def])));

qed "JN_insert";

Addsimps[JN_empty, JN_insert];

Goal "Init (JN i:I. F i) = (INT i:I. Init (F i))";

by (simp_tac (simpset() addsimps [JOIN_def]) 1);

qed "Init_JN";

Goal "Acts (JN i:I. F i) = insert Id (UN i:I. Acts (F i))";

by (auto_tac (claset(), simpset() addsimps [JOIN_def]));

qed "Acts_JN";

Addsimps [Init_JN, Acts_JN];

val prems = Goalw [JOIN_def]

    "[| I=J;  !!i. i:J ==> F i = G i |] ==> \

\    (JN i:I. F i) = (JN i:J. G i)";

by (asm_simp_tac (simpset() addsimps prems) 1);

qed "JN_cong";

Addcongs [JN_cong];

(** Algebraic laws **)

Goal "F Join G = G Join F";

by (simp_tac (simpset() addsimps [Join_def, Un_commute, Int_commute]) 1);

qed "Join_commute";

Goal "A Join (B Join C) = B Join (A Join C)";

by (simp_tac (simpset() addsimps Un_ac@Int_ac@[Join_def]) 1);

qed "Join_left_commute";

Goal "(F Join G) Join H = F Join (G Join H)";

by (simp_tac (simpset() addsimps Un_ac@[Join_def, Int_assoc]) 1);

qed "Join_assoc";

Goalw [Join_def, SKIP_def] "SKIP Join F = F";

by (rtac program_equalityI 1);

by (ALLGOALS (simp_tac (simpset() addsimps [insert_absorb])));

qed "Join_SKIP_left";

Goalw [Join_def, SKIP_def] "F Join SKIP = F";

by (rtac program_equalityI 1);

by (ALLGOALS (simp_tac (simpset() addsimps [insert_absorb])));

qed "Join_SKIP_right";

Addsimps [Join_SKIP_left, Join_SKIP_right];

Goalw [Join_def] "F Join F = F";

by (rtac program_equalityI 1);

by Auto_tac;

qed "Join_absorb";

Addsimps [Join_absorb];

Goalw [Join_def] "A Join (A Join B) = A Join B";

by (rtac program_equalityI 1);

by Auto_tac;

qed "Join_left_absorb";

(*Join is an AC-operator*)

val Join_ac = [Join_assoc, Join_left_absorb, Join_commute, Join_left_commute];

(*** JN laws ***)

(*Also follows by JN_insert and insert_absorb, but the proof is longer*)

Goal "k:I ==> F k Join (JN i:I. F i) = (JN i:I. F i)";

by (auto_tac (claset() addSIs [program_equalityI], simpset()));

qed "JN_absorb";

Goal "(JN i: I Un J. F i) = ((JN i: I. F i) Join (JN i:J. F i))";

by (auto_tac (claset() addSIs [program_equalityI], simpset()));

qed "JN_Un";

Goal "(JN i:I. c) = (if I={} then SKIP else c)";

by (auto_tac (claset() addSIs [program_equalityI], simpset()));

qed "JN_constant";

Goal "(JN i:I. F i Join G i) = (JN i:I. F i)  Join  (JN i:I. G i)";

by (auto_tac (claset() addSIs [program_equalityI], simpset()));

qed "JN_Join_distrib";

Goal "i : I ==> (JN i:I. F i Join G) = ((JN i:I. F i) Join G)";

by (asm_simp_tac (simpset() addsimps [JN_Join_distrib, JN_constant]) 1);

by Auto_tac;

qed "JN_Join_miniscope";

(*** Safety: co, stable, FP ***)

(*Fails if I={} because it collapses to SKIP : A co B*)

Goalw [constrains_def, JOIN_def]

    "i : I ==> (JN i:I. F i) : A co B = (ALL i:I. F i : A co B)";

by (Simp_tac 1);

by (Blast_tac 1);

qed "JN_constrains";

Goal "(F Join G : A co B) = (F : A co B & G : A co B)";

by (auto_tac

    (claset(),

     simpset() addsimps [constrains_def, Join_def]));

qed "Join_constrains";

(*Analogous weak versions FAIL; see Misra [1994] 5.4.1, Substitution Axiom.

  reachable (F Join G) could be much bigger than reachable F, reachable G

*)

Goal "[| F : A co A';  G : B co B' |] \

\     ==> F Join G : (A Int B) co (A' Un B')";

by (simp_tac (simpset() addsimps [Join_constrains]) 1);

by (blast_tac (claset() addIs [constrains_weaken]) 1);

qed "Join_constrains_weaken";

Goal "[| ALL i:I. F i : A i co A' i;  i: I |] \

\     ==> (JN i:I. F i) : (INT i:I. A i) co (UN i:I. A' i)";

by (asm_simp_tac (simpset() addsimps [JN_constrains]) 1);

by (blast_tac (claset() addIs [constrains_weaken]) 1);

qed "JN_constrains_weaken";

Goal "i : I ==> \

\     (JN i:I. F i) : stable A = (ALL i:I. F i : stable A)";

by (asm_simp_tac (simpset() addsimps [stable_def, JN_constrains]) 1);

qed "JN_stable";

Goal "[| ALL i:I. F i : invariant A;  i : I |]  \

\      ==> (JN i:I. F i) : invariant A";

by (asm_full_simp_tac (simpset() addsimps [invariant_def, JN_stable]) 1);

by (Blast_tac 1);

bind_thm ("invariant_JN_I", ballI RS result());

Goal "F Join G : stable A = \

\     (F : stable A & G : stable A)";

by (simp_tac (simpset() addsimps [stable_def, Join_constrains]) 1);

qed "Join_stable";

Goal "[| F : invariant A; G : invariant A |]  \

\     ==> F Join G : invariant A";

by (full_simp_tac (simpset() addsimps [invariant_def, Join_stable]) 1);

by (Blast_tac 1);

qed "invariant_JoinI";

Goal "i : I ==> FP (JN i:I. F i) = (INT i:I. FP (F i))";

by (asm_simp_tac (simpset() addsimps [FP_def, JN_stable, INTER_def]) 1);

qed "FP_JN";

(*** Progress: transient, ensures ***)

Goal "i : I ==> \

\   (JN i:I. F i) : transient A = (EX i:I. F i : transient A)";

by (auto_tac (claset(),

	      simpset() addsimps [transient_def, JOIN_def]));

qed "JN_transient";

Goal "F Join G : transient A = \

\     (F : transient A | G : transient A)";

by (auto_tac (claset(),

	      simpset() addsimps [bex_Un, transient_def,

				  Join_def]));

qed "Join_transient";

Goal "i : I ==> \

\     (JN i:I. F i) : A ensures B = \

\     ((ALL i:I. F i : (A-B) co (A Un B)) & \

\      (EX i:I. F i : A ensures B))";

by (auto_tac (claset(),

	      simpset() addsimps [ensures_def, JN_constrains, JN_transient]));

qed "JN_ensures";

Goalw [ensures_def]

     "F Join G : A ensures B =     \

\     (F : (A-B) co (A Un B) & \

\      G : (A-B) co (A Un B) & \

\      (F : A ensures B | G : A ensures B))";

by (auto_tac (claset(),

	      simpset() addsimps [Join_constrains, Join_transient]));

qed "Join_ensures";

Goalw [stable_def, constrains_def, Join_def]

    "[| F : stable A;  G : A co A' |] \

\    ==> F Join G : A co A'";

by (asm_full_simp_tac (simpset() addsimps [ball_Un]) 1);

by (Blast_tac 1);

qed "stable_Join_constrains";

(*Premise for G cannot use Always because  F: Stable A  is weaker than

  G : stable A *)

Goal "[| F : stable A;  G : invariant A |] ==> F Join G : Always A";

by (full_simp_tac (simpset() addsimps [Always_def, invariant_def, 

				       Stable_eq_stable, Join_stable]) 1);

by (force_tac(claset() addIs [stable_reachable, stable_Int],

	      simpset()) 1);

qed "stable_Join_Always";

Goal "[| F : stable A;  G : A ensures B |] ==> F Join G : A ensures B";

by (asm_simp_tac (simpset() addsimps [Join_ensures]) 1);

by (asm_full_simp_tac (simpset() addsimps [stable_def, ensures_def]) 1);

by (etac constrains_weaken 1);

by Auto_tac;

qed "stable_Join_ensures1";

(*As above, but exchanging the roles of F and G*)

Goal "[| F : A ensures B;  G : stable A |] ==> F Join G : A ensures B";

by (stac Join_commute 1);

by (blast_tac (claset() addIs [stable_Join_ensures1]) 1);

qed "stable_Join_ensures2";

(** Diff and localTo **)

Goalw [Join_def, Diff_def] "F Join (Diff G (Acts F)) = F Join G";

by (rtac program_equalityI 1);

by Auto_tac;

qed "Join_Diff2";

Goalw [Diff_def, Disjoint_def] "Disjoint F (Diff G (Acts F))";

by Auto_tac;

qed "Diff_Disjoint";

Goal "[| F Join G : v localTo F;  Disjoint F G |] \

\     ==> G : (INT z. stable {s. v s = z})";

by (asm_full_simp_tac 

    (simpset() addsimps [localTo_def, Diff_def, Disjoint_def,

			 stable_def, constrains_def]) 1);

by (Blast_tac 1);

qed "localTo_imp_stable";

Goal "[| F Join G : v localTo F;  (s,s') : act;  \

\        act : Acts G;  Disjoint F G |] ==> v s' = v s";

by (asm_full_simp_tac 

    (simpset() addsimps [localTo_def, Diff_def, Disjoint_def,

			 stable_def, constrains_def]) 1);

by (Blast_tac 1);

qed "localTo_imp_equals";

Goalw [localTo_def, stable_def, constrains_def]

     "v localTo F <= (f o v) localTo F";

by (Clarify_tac 1);

by (force_tac (claset() addSEs [allE, ballE], simpset()) 1);

qed "localTo_imp_o_localTo";

(*** Higher-level rules involving localTo and Join ***)

Goal "[| F : {s. P (v s) (w s)} co {s. P' (v s) (w s)};   \

\        F Join G : v localTo F;       \

\        F Join G : w localTo F;       \

\        Disjoint F G |]               \

\     ==> F Join G : {s. P (v s) (w s)} co {s. P' (v s) (w s)}";

by (auto_tac (claset(), simpset() addsimps [constrains_def]));

by (REPEAT_FIRST (dtac localTo_imp_equals THEN' REPEAT1 o atac));

by Auto_tac;

qed "constrains_localTo_constrains2";

Goalw [stable_def]

     "[| F : stable {s. P (v s) (w s)};   \

\        F Join G : v localTo F;       \

\        F Join G : w localTo F;       \

\        Disjoint F G |]               \

\     ==> F Join G : stable {s. P (v s) (w s)}";

by (blast_tac (claset() addIs [constrains_localTo_constrains2]) 1);

qed "stable_localTo_stable2";

Goal "(UN k. {s. f s = k}) = UNIV";

by (Blast_tac 1);

qed "UN_eq_UNIV";

Goal "[| F : stable {s. v s <= w s};   \

\        F Join G : v localTo F;       \

\        F Join G : Increasing w;      \

\        Disjoint F G |]               \

\     ==> F Join G : Stable {s. v s <= w s}";

by (safe_tac (claset() addSDs [localTo_imp_stable]));

by (rewrite_goals_tac [stable_def, Stable_def, Increasing_def]);

by (subgoal_tac "ALL k: UNIV. ?H : ({s. v s = k} Int ?AA) Co ?AA" 1);

by (dtac ball_Constrains_UN 1);

by (full_simp_tac (simpset() addsimps [UN_eq_UNIV]) 1);

by (rtac ballI 1);

by (subgoal_tac "F Join G : ({s. v s = k} Int {s. v s <= w s}) co \

\                                      ({s. v s = k} Un {s. v s <= w s})" 1);

by (asm_simp_tac (simpset() addsimps [Join_constrains]) 2);

by (blast_tac (claset() addIs [constrains_weaken]) 2);

by (dtac (constrains_imp_Constrains RS Constrains_Int) 1 THEN etac INT_D 1);

by (etac Constrains_weaken 2);

by Auto_tac;

qed "Increasing_localTo_Stable";