| author | wenzelm |
| Sat, 12 Nov 2011 20:14:09 +0100 | |
| changeset 45476 | 6f9e24376ffd |
| parent 41589 | bbd861837ebc |
| child 46459 | 73823dbbecc4 |
| permissions | -rw-r--r-- |
| 8177 | 1 |
(* Title: HOL/IMPP/Natural.thy |
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Author: David von Oheimb (based on a theory by Tobias Nipkow et al), TUM |
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*) |
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header {* Natural semantics of commands *}
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theory Natural |
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imports Com |
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begin |
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(** Execution of commands **) |
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consts |
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newlocs :: locals |
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setlocs :: "state => locals => state" |
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getlocs :: "state => locals" |
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update :: "state => vname => val => state" ("_/[_/::=/_]" [900,0,0] 900)
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abbreviation |
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loc :: "state => locals" ("_<_>" [75,0] 75) where
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"s<X> == getlocs s X" |
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inductive |
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evalc :: "[com,state, state] => bool" ("<_,_>/ -c-> _" [0,0, 51] 51)
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where |
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Skip: "<SKIP,s> -c-> s" |
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| Assign: "<X :== a,s> -c-> s[X::=a s]" |
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| Local: "<c, s0[Loc Y::= a s0]> -c-> s1 ==> |
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<LOCAL Y := a IN c, s0> -c-> s1[Loc Y::=s0<Y>]" |
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| Semi: "[| <c0,s0> -c-> s1; <c1,s1> -c-> s2 |] ==> |
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<c0;; c1, s0> -c-> s2" |
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| IfTrue: "[| b s; <c0,s> -c-> s1 |] ==> |
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<IF b THEN c0 ELSE c1, s> -c-> s1" |
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| IfFalse: "[| ~b s; <c1,s> -c-> s1 |] ==> |
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<IF b THEN c0 ELSE c1, s> -c-> s1" |
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| WhileFalse: "~b s ==> <WHILE b DO c,s> -c-> s" |
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| WhileTrue: "[| b s0; <c,s0> -c-> s1; <WHILE b DO c, s1> -c-> s2 |] ==> |
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<WHILE b DO c, s0> -c-> s2" |
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| Body: "<the (body pn), s0> -c-> s1 ==> |
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<BODY pn, s0> -c-> s1" |
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| Call: "<BODY pn, (setlocs s0 newlocs)[Loc Arg::=a s0]> -c-> s1 ==> |
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<X:=CALL pn(a), s0> -c-> (setlocs s1 (getlocs s0)) |
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[X::=s1<Res>]" |
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inductive |
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evaln :: "[com,state,nat,state] => bool" ("<_,_>/ -_-> _" [0,0,0,51] 51)
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where |
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Skip: "<SKIP,s> -n-> s" |
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| Assign: "<X :== a,s> -n-> s[X::=a s]" |
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| Local: "<c, s0[Loc Y::= a s0]> -n-> s1 ==> |
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<LOCAL Y := a IN c, s0> -n-> s1[Loc Y::=s0<Y>]" |
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| Semi: "[| <c0,s0> -n-> s1; <c1,s1> -n-> s2 |] ==> |
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<c0;; c1, s0> -n-> s2" |
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| IfTrue: "[| b s; <c0,s> -n-> s1 |] ==> |
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<IF b THEN c0 ELSE c1, s> -n-> s1" |
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| IfFalse: "[| ~b s; <c1,s> -n-> s1 |] ==> |
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<IF b THEN c0 ELSE c1, s> -n-> s1" |
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| WhileFalse: "~b s ==> <WHILE b DO c,s> -n-> s" |
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| WhileTrue: "[| b s0; <c,s0> -n-> s1; <WHILE b DO c, s1> -n-> s2 |] ==> |
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<WHILE b DO c, s0> -n-> s2" |
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| Body: "<the (body pn), s0> - n-> s1 ==> |
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<BODY pn, s0> -Suc n-> s1" |
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| Call: "<BODY pn, (setlocs s0 newlocs)[Loc Arg::=a s0]> -n-> s1 ==> |
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<X:=CALL pn(a), s0> -n-> (setlocs s1 (getlocs s0)) |
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[X::=s1<Res>]" |
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inductive_cases evalc_elim_cases: |
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"<SKIP,s> -c-> t" "<X:==a,s> -c-> t" "<LOCAL Y:=a IN c,s> -c-> t" |
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"<c1;;c2,s> -c-> t" "<IF b THEN c1 ELSE c2,s> -c-> t" |
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"<BODY P,s> -c-> s1" "<X:=CALL P(a),s> -c-> s1" |
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inductive_cases evaln_elim_cases: |
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"<SKIP,s> -n-> t" "<X:==a,s> -n-> t" "<LOCAL Y:=a IN c,s> -n-> t" |
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"<c1;;c2,s> -n-> t" "<IF b THEN c1 ELSE c2,s> -n-> t" |
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"<BODY P,s> -n-> s1" "<X:=CALL P(a),s> -n-> s1" |
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inductive_cases evalc_WHILE_case: "<WHILE b DO c,s> -c-> t" |
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inductive_cases evaln_WHILE_case: "<WHILE b DO c,s> -n-> t" |
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declare evalc.intros [intro] |
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declare evaln.intros [intro] |
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declare evalc_elim_cases [elim!] |
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declare evaln_elim_cases [elim!] |
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(* evaluation of com is deterministic *) |
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lemma com_det [rule_format (no_asm)]: "<c,s> -c-> t ==> (!u. <c,s> -c-> u --> u=t)" |
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apply (erule evalc.induct) |
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apply (erule_tac [8] V = "<?c,s1> -c-> s2" in thin_rl) |
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(*blast needs unify_search_bound = 40*) |
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apply (best elim: evalc_WHILE_case)+ |
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done |
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lemma evaln_evalc: "<c,s> -n-> t ==> <c,s> -c-> t" |
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apply (erule evaln.induct) |
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apply (tactic {* ALLGOALS (resolve_tac @{thms evalc.intros} THEN_ALL_NEW atac) *})
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done |
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lemma Suc_le_D_lemma: "[| Suc n <= m'; (!!m. n <= m ==> P (Suc m)) |] ==> P m'" |
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apply (frule Suc_le_D) |
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apply blast |
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done |
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lemma evaln_nonstrict [rule_format]: "<c,s> -n-> t ==> !m. n<=m --> <c,s> -m-> t" |
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apply (erule evaln.induct) |
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apply (tactic {* ALLGOALS (EVERY'[strip_tac,TRY o etac @{thm Suc_le_D_lemma}, REPEAT o smp_tac 1]) *})
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apply (tactic {* ALLGOALS (resolve_tac @{thms evaln.intros} THEN_ALL_NEW atac) *})
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done |
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lemma evaln_Suc: "<c,s> -n-> s' ==> <c,s> -Suc n-> s'" |
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apply (erule evaln_nonstrict) |
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apply auto |
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done |
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lemma evaln_max2: "[| <c1,s1> -n1-> t1; <c2,s2> -n2-> t2 |] ==> |
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? n. <c1,s1> -n -> t1 & <c2,s2> -n -> t2" |
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apply (cut_tac m = "n1" and n = "n2" in nat_le_linear) |
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apply (blast dest: evaln_nonstrict) |
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done |
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lemma evalc_evaln: "<c,s> -c-> t ==> ? n. <c,s> -n-> t" |
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apply (erule evalc.induct) |
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apply (tactic {* ALLGOALS (REPEAT o etac exE) *})
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apply (tactic {* TRYALL (EVERY' [datac @{thm evaln_max2} 1, REPEAT o eresolve_tac [exE, conjE]]) *})
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apply (tactic {* ALLGOALS (rtac exI THEN' resolve_tac @{thms evaln.intros} THEN_ALL_NEW atac) *})
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done |
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lemma eval_eq: "<c,s> -c-> t = (? n. <c,s> -n-> t)" |
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apply (fast elim: evalc_evaln evaln_evalc) |
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done |
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end |