author  huffman 
Thu, 14 Jul 2005 01:04:30 +0200  
changeset 16823  13f3768a6f14 
parent 15798  016f3be5a5ec 
child 16853  33b886cbdc8f 
permissions  rwrr 
10781  1 
(* Title: TFL/rules.ML 
10769  2 
ID: $Id$ 
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Author: Konrad Slind, Cambridge University Computer Laboratory 

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Copyright 1997 University of Cambridge 

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Emulation of HOL inference rules for TFL 

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*) 

8 

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signature RULES = 

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sig 

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val dest_thm : thm > term list * term 

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(* Inference rules *) 

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val REFL :cterm > thm 

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val ASSUME :cterm > thm 

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val MP :thm > thm > thm 

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val MATCH_MP :thm > thm > thm 

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val CONJUNCT1 :thm > thm 

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val CONJUNCT2 :thm > thm 

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val CONJUNCTS :thm > thm list 

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val DISCH :cterm > thm > thm 

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val UNDISCH :thm > thm 

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val SPEC :cterm > thm > thm 

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val ISPEC :cterm > thm > thm 

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val ISPECL :cterm list > thm > thm 

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val GEN :cterm > thm > thm 

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val GENL :cterm list > thm > thm 

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val LIST_CONJ :thm list > thm 

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val SYM : thm > thm 

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val DISCH_ALL : thm > thm 

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val FILTER_DISCH_ALL : (term > bool) > thm > thm 

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val SPEC_ALL : thm > thm 

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val GEN_ALL : thm > thm 

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val IMP_TRANS : thm > thm > thm 

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val PROVE_HYP : thm > thm > thm 

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val CHOOSE : cterm * thm > thm > thm 

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val EXISTS : cterm * cterm > thm > thm 

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val EXISTL : cterm list > thm > thm 

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val IT_EXISTS : (cterm*cterm) list > thm > thm 

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val EVEN_ORS : thm list > thm list 

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val DISJ_CASESL : thm > thm list > thm 

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val list_beta_conv : cterm > cterm list > thm 

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val SUBS : thm list > thm > thm 

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val simpl_conv : simpset > thm list > cterm > thm 

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val rbeta : thm > thm 

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(* For debugging my isabelle solver in the conditional rewriter *) 

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val term_ref : term list ref 

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val thm_ref : thm list ref 

15021  54 
val ss_ref : simpset list ref 
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val tracing : bool ref 
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val CONTEXT_REWRITE_RULE : term * term list * thm * thm list 

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> thm > thm * term list 

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val RIGHT_ASSOC : thm > thm 

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11632  60 
val prove : bool > cterm * tactic > thm 
10769  61 
end; 
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structure Rules: RULES = 

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struct 

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structure S = USyntax; 

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structure U = Utils; 

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structure D = Dcterm; 

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fun RULES_ERR func mesg = U.ERR {module = "Rules", func = func, mesg = mesg}; 

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fun cconcl thm = D.drop_prop (#prop (Thm.crep_thm thm)); 

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fun chyps thm = map D.drop_prop (#hyps (Thm.crep_thm thm)); 

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fun dest_thm thm = 

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let val {prop,hyps,...} = Thm.rep_thm thm 

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in (map HOLogic.dest_Trueprop hyps, HOLogic.dest_Trueprop prop) end 

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handle TERM _ => raise RULES_ERR "dest_thm" "missing Trueprop"; 

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(* Inference rules *) 

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(* 

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* Equality (one step) 

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**) 

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fun REFL tm = Thm.reflexive tm RS meta_eq_to_obj_eq 

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handle THM (msg, _, _) => raise RULES_ERR "REFL" msg; 

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fun SYM thm = thm RS sym 

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handle THM (msg, _, _) => raise RULES_ERR "SYM" msg; 

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fun ALPHA thm ctm1 = 

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let 

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val ctm2 = Thm.cprop_of thm; 

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val ctm2_eq = Thm.reflexive ctm2; 

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val ctm1_eq = Thm.reflexive ctm1; 

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in Thm.equal_elim (Thm.transitive ctm2_eq ctm1_eq) thm end 

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handle THM (msg, _, _) => raise RULES_ERR "ALPHA" msg; 

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fun rbeta th = 

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(case D.strip_comb (cconcl th) of 

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(_, [l, r]) => Thm.transitive th (Thm.beta_conversion false r) 

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 _ => raise RULES_ERR "rbeta" ""); 

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(* 

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* Implication and the assumption list 

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* 

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* Assumptions get stuck on the metalanguage assumption list. Implications 

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* are in the object language, so discharging an assumption "A" from theorem 

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* "B" results in something that looks like "A > B". 

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**) 

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fun ASSUME ctm = Thm.assume (D.mk_prop ctm); 

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(* 

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* Implication in TFL is >. Metalanguage implication (==>) is only used 

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* in the implementation of some of the inference rules below. 

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**) 

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fun MP th1 th2 = th2 RS (th1 RS mp) 

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handle THM (msg, _, _) => raise RULES_ERR "MP" msg; 

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(*forces the first argument to be a proposition if necessary*) 

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fun DISCH tm thm = Thm.implies_intr (D.mk_prop tm) thm COMP impI 

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handle THM (msg, _, _) => raise RULES_ERR "DISCH" msg; 

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fun DISCH_ALL thm = U.itlist DISCH (#hyps (Thm.crep_thm thm)) thm; 

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fun FILTER_DISCH_ALL P thm = 

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let fun check tm = P (#t (Thm.rep_cterm tm)) 

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in foldr (fn (tm,th) => if check tm then DISCH tm th else th) 
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thm (chyps thm) 
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end; 
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(* freezeT expensive! *) 

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fun UNDISCH thm = 

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let val tm = D.mk_prop (#1 (D.dest_imp (cconcl (Thm.freezeT thm)))) 

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in Thm.implies_elim (thm RS mp) (ASSUME tm) end 

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handle U.ERR _ => raise RULES_ERR "UNDISCH" "" 

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 THM _ => raise RULES_ERR "UNDISCH" ""; 

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fun PROVE_HYP ath bth = MP (DISCH (cconcl ath) bth) ath; 

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fun IMP_TRANS th1 th2 = th2 RS (th1 RS Thms.imp_trans) 

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handle THM (msg, _, _) => raise RULES_ERR "IMP_TRANS" msg; 

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(* 

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* Conjunction 

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**) 

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fun CONJUNCT1 thm = thm RS conjunct1 

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handle THM (msg, _, _) => raise RULES_ERR "CONJUNCT1" msg; 

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fun CONJUNCT2 thm = thm RS conjunct2 

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handle THM (msg, _, _) => raise RULES_ERR "CONJUNCT2" msg; 

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fun CONJUNCTS th = CONJUNCTS (CONJUNCT1 th) @ CONJUNCTS (CONJUNCT2 th) handle U.ERR _ => [th]; 

164 

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fun LIST_CONJ [] = raise RULES_ERR "LIST_CONJ" "empty list" 

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 LIST_CONJ [th] = th 

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 LIST_CONJ (th :: rst) = MP (MP (conjI COMP (impI RS impI)) th) (LIST_CONJ rst) 

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handle THM (msg, _, _) => raise RULES_ERR "LIST_CONJ" msg; 

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(* 

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* Disjunction 

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**) 

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local val {prop,sign,...} = rep_thm disjI1 

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val [P,Q] = term_vars prop 

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val disj1 = Thm.forall_intr (Thm.cterm_of sign Q) disjI1 

177 
in 

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fun DISJ1 thm tm = thm RS (forall_elim (D.drop_prop tm) disj1) 

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handle THM (msg, _, _) => raise RULES_ERR "DISJ1" msg; 

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end; 

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local val {prop,sign,...} = rep_thm disjI2 

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val [P,Q] = term_vars prop 

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val disj2 = Thm.forall_intr (Thm.cterm_of sign P) disjI2 

185 
in 

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fun DISJ2 tm thm = thm RS (forall_elim (D.drop_prop tm) disj2) 

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handle THM (msg, _, _) => raise RULES_ERR "DISJ2" msg; 

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end; 

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(* 

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* 

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* A1  M1, ..., An  Mn 

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*  

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* [A1  M1 \/ ... \/ Mn, ..., An  M1 \/ ... \/ Mn] 

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* 

197 
**) 

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fun EVEN_ORS thms = 

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let fun blue ldisjs [] _ = [] 

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 blue ldisjs (th::rst) rdisjs = 

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let val tail = tl rdisjs 

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val rdisj_tl = D.list_mk_disj tail 

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in U.itlist DISJ2 ldisjs (DISJ1 th rdisj_tl) 

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:: blue (ldisjs @ [cconcl th]) rst tail 

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end handle U.ERR _ => [U.itlist DISJ2 ldisjs th] 

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in blue [] thms (map cconcl thms) end; 

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(* 

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* 

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* A  P \/ Q B,P  R C,Q  R 

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*  

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* A U B U C  R 

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* 

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**) 

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fun DISJ_CASES th1 th2 th3 = 

220 
let 

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val c = D.drop_prop (cconcl th1); 

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val (disj1, disj2) = D.dest_disj c; 

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val th2' = DISCH disj1 th2; 

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val th3' = DISCH disj2 th3; 

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in 

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th3' RS (th2' RS (th1 RS Thms.tfl_disjE)) 

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handle THM (msg, _, _) => raise RULES_ERR "DISJ_CASES" msg 

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end; 

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(* 

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* 

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*  A1 \/ ... \/ An [A1  M, ..., An  M] 

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*  

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*  M 

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* 

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* Note. The list of theorems may be all jumbled up, so we have to 

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* first organize it to align with the first argument (the disjunctive 

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* theorem). 

240 
**) 

241 

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fun organize eq = (* a bit slow  analogous to insertion sort *) 

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let fun extract a alist = 

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let fun ex (_,[]) = raise RULES_ERR "organize" "not a permutation.1" 

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 ex(left,h::t) = if (eq h a) then (h,rev left@t) else ex(h::left,t) 

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in ex ([],alist) 

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end 

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fun place [] [] = [] 

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 place (a::rst) alist = 

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let val (item,next) = extract a alist 

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in item::place rst next 

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end 

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 place _ _ = raise RULES_ERR "organize" "not a permutation.2" 

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in place 

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end; 

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(* freezeT expensive! *) 

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fun DISJ_CASESL disjth thl = 

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let val c = cconcl disjth 

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fun eq th atm = exists (fn t => HOLogic.dest_Trueprop t 

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aconv term_of atm) 

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(#hyps(rep_thm th)) 

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val tml = D.strip_disj c 

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fun DL th [] = raise RULES_ERR "DISJ_CASESL" "no cases" 

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 DL th [th1] = PROVE_HYP th th1 

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 DL th [th1,th2] = DISJ_CASES th th1 th2 

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 DL th (th1::rst) = 

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let val tm = #2(D.dest_disj(D.drop_prop(cconcl th))) 

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in DISJ_CASES th th1 (DL (ASSUME tm) rst) end 

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in DL (freezeT disjth) (organize eq tml thl) 

270 
end; 

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(* 

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* Universals 

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**) 

276 
local (* this is fragile *) 

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val {prop,sign,...} = rep_thm spec 

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val x = hd (tl (term_vars prop)) 

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val cTV = ctyp_of sign (type_of x) 
10769  280 
val gspec = forall_intr (cterm_of sign x) spec 
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in 

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fun SPEC tm thm = 

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let val {sign,T,...} = rep_cterm tm 

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val gspec' = instantiate ([(cTV, ctyp_of sign T)], []) gspec 
10769  285 
in 
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thm RS (forall_elim tm gspec') 

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end 

288 
end; 

289 

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fun SPEC_ALL thm = U.rev_itlist SPEC (#1(D.strip_forall(cconcl thm))) thm; 

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292 
val ISPEC = SPEC 

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val ISPECL = U.rev_itlist ISPEC; 

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(* Not optimized! Too complicated. *) 

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local val {prop,sign,...} = rep_thm allI 

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val [P] = add_term_vars (prop, []) 

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fun cty_theta s = map (fn (i, (S, ty)) => (ctyp_of s (TVar (i, S)), ctyp_of s ty)) 
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fun ctm_theta s = map (fn (i, (_, tm2)) => 
10769  300 
let val ctm2 = cterm_of s tm2 
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in (cterm_of s (Var(i,#T(rep_cterm ctm2))), ctm2) 

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end) 

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fun certify s (ty_theta,tm_theta) = 
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(cty_theta s (Vartab.dest ty_theta), 
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ctm_theta s (Vartab.dest tm_theta)) 
10769  306 
in 
307 
fun GEN v th = 

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let val gth = forall_intr v th 

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val {prop=Const("all",_)$Abs(x,ty,rst),sign,...} = rep_thm gth 

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val P' = Abs(x,ty, HOLogic.dest_Trueprop rst) (* get rid of trueprop *) 

14643  311 
val tsig = Sign.tsig_of sign 
10769  312 
val theta = Pattern.match tsig (P,P') 
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val allI2 = instantiate (certify sign theta) allI 

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val thm = Thm.implies_elim allI2 gth 

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val {prop = tp $ (A $ Abs(_,_,M)),sign,...} = rep_thm thm 

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val prop' = tp $ (A $ Abs(x,ty,M)) 

317 
in ALPHA thm (cterm_of sign prop') 

318 
end 

319 
end; 

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321 
val GENL = U.itlist GEN; 

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323 
fun GEN_ALL thm = 

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let val {prop,sign,...} = rep_thm thm 

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val tycheck = cterm_of sign 

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val vlist = map tycheck (add_term_vars (prop, [])) 

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in GENL vlist thm 

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end; 

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fun MATCH_MP th1 th2 = 

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if (D.is_forall (D.drop_prop(cconcl th1))) 

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then MATCH_MP (th1 RS spec) th2 

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else MP th1 th2; 

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(* 

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* Existentials 

339 
**) 

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(* 

344 
* Existential elimination 

345 
* 

346 
* A1  ?x.t[x] , A2, "t[v]"  t' 

347 
*  (variable v occurs nowhere) 

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* A1 u A2  t' 

349 
* 

350 
**) 

351 

352 
fun CHOOSE (fvar, exth) fact = 

353 
let 

354 
val lam = #2 (D.dest_comb (D.drop_prop (cconcl exth))) 

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val redex = D.capply lam fvar 

356 
val {sign, t = t$u,...} = Thm.rep_cterm redex 

357 
val residue = Thm.cterm_of sign (betapply (t, u)) 

358 
in 

359 
GEN fvar (DISCH residue fact) RS (exth RS Thms.choose_thm) 

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handle THM (msg, _, _) => raise RULES_ERR "CHOOSE" msg 

361 
end; 

362 

363 
local val {prop,sign,...} = rep_thm exI 

364 
val [P,x] = term_vars prop 

365 
in 

366 
fun EXISTS (template,witness) thm = 

367 
let val {prop,sign,...} = rep_thm thm 

368 
val P' = cterm_of sign P 

369 
val x' = cterm_of sign x 

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val abstr = #2 (D.dest_comb template) 

371 
in 

372 
thm RS (cterm_instantiate[(P',abstr), (x',witness)] exI) 

373 
handle THM (msg, _, _) => raise RULES_ERR "EXISTS" msg 

374 
end 

375 
end; 

376 

377 
(* 

378 
* 

379 
* A  M 

380 
*  [v_1,...,v_n] 

381 
* A  ?v1...v_n. M 

382 
* 

383 
**) 

384 

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fun EXISTL vlist th = 

386 
U.itlist (fn v => fn thm => EXISTS(D.mk_exists(v,cconcl thm), v) thm) 

387 
vlist th; 

388 

389 

390 
(* 

391 
* 

392 
* A  M[x_1,...,x_n] 

393 
*  [(x > y)_1,...,(x > y)_n] 

394 
* A  ?y_1...y_n. M 

395 
* 

396 
**) 

397 
(* Could be improved, but needs "subst_free" for certified terms *) 

398 

399 
fun IT_EXISTS blist th = 

400 
let val {sign,...} = rep_thm th 

401 
val tych = cterm_of sign 

402 
val detype = #t o rep_cterm 

403 
val blist' = map (fn (x,y) => (detype x, detype y)) blist 

404 
fun ?v M = cterm_of sign (S.mk_exists{Bvar=v,Body = M}) 

405 

406 
in 

407 
U.itlist (fn (b as (r1,r2)) => fn thm => 

408 
EXISTS(?r2(subst_free[b] 

409 
(HOLogic.dest_Trueprop(#prop(rep_thm thm)))), tych r1) 

410 
thm) 

411 
blist' th 

412 
end; 

413 

414 
(* 

415 
* Faster version, that fails for some as yet unknown reason 

416 
* fun IT_EXISTS blist th = 

417 
* let val {sign,...} = rep_thm th 

418 
* val tych = cterm_of sign 

419 
* fun detype (x,y) = ((#t o rep_cterm) x, (#t o rep_cterm) y) 

420 
* in 

421 
* fold (fn (b as (r1,r2), thm) => 

422 
* EXISTS(D.mk_exists(r2, tych(subst_free[detype b](#t(rep_cterm(cconcl thm))))), 

423 
* r1) thm) blist th 

424 
* end; 

425 
**) 

426 

427 
(* 

428 
* Rewriting 

429 
**) 

430 

431 
fun SUBS thl = 

432 
rewrite_rule (map (fn th => th RS eq_reflection handle THM _ => th) thl); 

433 

15531  434 
val rew_conv = MetaSimplifier.rewrite_cterm (true, false, false) (K (K NONE)); 
15021  435 

10769  436 
fun simpl_conv ss thl ctm = 
15021  437 
rew_conv (ss addsimps thl) ctm RS meta_eq_to_obj_eq; 
438 

10769  439 

440 
val RIGHT_ASSOC = rewrite_rule [Thms.disj_assoc]; 

441 

442 

443 

444 
(* 

445 
* TERMINATION CONDITION EXTRACTION 

446 
**) 

447 

448 

449 
(* Object language quantifier, i.e., "!" *) 

450 
fun Forall v M = S.mk_forall{Bvar=v, Body=M}; 

451 

452 

453 
(* Fragile: it's a cong if it is not "R y x ==> cut f R x y = f y" *) 

454 
fun is_cong thm = 

455 
let val {prop, ...} = rep_thm thm 

456 
in case prop 

457 
of (Const("==>",_)$(Const("Trueprop",_)$ _) $ 

458 
(Const("==",_) $ (Const ("Wellfounded_Recursion.cut",_) $ f $ R $ a $ x) $ _)) => false 

459 
 _ => true 

460 
end; 

461 

462 

463 

464 
fun dest_equal(Const ("==",_) $ 

465 
(Const ("Trueprop",_) $ lhs) 

466 
$ (Const ("Trueprop",_) $ rhs)) = {lhs=lhs, rhs=rhs} 

467 
 dest_equal(Const ("==",_) $ lhs $ rhs) = {lhs=lhs, rhs=rhs} 

468 
 dest_equal tm = S.dest_eq tm; 

469 

470 
fun get_lhs tm = #lhs(dest_equal (HOLogic.dest_Trueprop tm)); 

471 

472 
fun dest_all used (Const("all",_) $ (a as Abs _)) = S.dest_abs used a 

473 
 dest_all _ _ = raise RULES_ERR "dest_all" "not a !!"; 

474 

475 
val is_all = can (dest_all []); 

476 

477 
fun strip_all used fm = 

478 
if (is_all fm) 

479 
then let val ({Bvar, Body}, used') = dest_all used fm 

480 
val (bvs, core, used'') = strip_all used' Body 

481 
in ((Bvar::bvs), core, used'') 

482 
end 

483 
else ([], fm, used); 

484 

485 
fun break_all(Const("all",_) $ Abs (_,_,body)) = body 

486 
 break_all _ = raise RULES_ERR "break_all" "not a !!"; 

487 

488 
fun list_break_all(Const("all",_) $ Abs (s,ty,body)) = 

489 
let val (L,core) = list_break_all body 

490 
in ((s,ty)::L, core) 

491 
end 

492 
 list_break_all tm = ([],tm); 

493 

494 
(* 

495 
* Rename a term of the form 

496 
* 

497 
* !!x1 ...xn. x1=M1 ==> ... ==> xn=Mn 

498 
* ==> ((%v1...vn. Q) x1 ... xn = g x1 ... xn. 

499 
* to one of 

500 
* 

501 
* !!v1 ... vn. v1=M1 ==> ... ==> vn=Mn 

502 
* ==> ((%v1...vn. Q) v1 ... vn = g v1 ... vn. 

503 
* 

504 
* This prevents name problems in extraction, and helps the result to read 

505 
* better. There is a problem with varstructs, since they can introduce more 

506 
* than n variables, and some extra reasoning needs to be done. 

507 
**) 

508 

509 
fun get ([],_,L) = rev L 

510 
 get (ant::rst,n,L) = 

511 
case (list_break_all ant) 

512 
of ([],_) => get (rst, n+1,L) 

513 
 (vlist,body) => 

514 
let val eq = Logic.strip_imp_concl body 

515 
val (f,args) = S.strip_comb (get_lhs eq) 

516 
val (vstrl,_) = S.strip_abs f 

517 
val names = variantlist (map (#1 o dest_Free) vstrl, 

518 
add_term_names(body, [])) 

519 
in get (rst, n+1, (names,n)::L) end 

520 
handle TERM _ => get (rst, n+1, L) 

521 
 U.ERR _ => get (rst, n+1, L); 

522 

523 
(* Note: rename_params_rule counts from 1, not 0 *) 

524 
fun rename thm = 

525 
let val {prop,sign,...} = rep_thm thm 

526 
val tych = cterm_of sign 

527 
val ants = Logic.strip_imp_prems prop 

528 
val news = get (ants,1,[]) 

529 
in 

530 
U.rev_itlist rename_params_rule news thm 

531 
end; 

532 

533 

534 
(* 

535 
* Betaconversion to the rhs of an equation (taken from hol90/drule.sml) 

536 
**) 

537 

538 
fun list_beta_conv tm = 

539 
let fun rbeta th = Thm.transitive th (beta_conversion false (#2(D.dest_eq(cconcl th)))) 

540 
fun iter [] = Thm.reflexive tm 

541 
 iter (v::rst) = rbeta (combination(iter rst) (Thm.reflexive v)) 

542 
in iter end; 

543 

544 

545 
(* 

546 
* Trace information for the rewriter 

547 
**) 

548 
val term_ref = ref[] : term list ref 

15021  549 
val ss_ref = ref [] : simpset list ref; 
10769  550 
val thm_ref = ref [] : thm list ref; 
551 
val tracing = ref false; 

552 

553 
fun say s = if !tracing then writeln s else (); 

554 

555 
fun print_thms s L = 

556 
say (cat_lines (s :: map string_of_thm L)); 

557 

558 
fun print_cterms s L = 

559 
say (cat_lines (s :: map string_of_cterm L)); 

560 

561 

562 
(* 

563 
* General abstraction handlers, should probably go in USyntax. 

564 
**) 

565 
fun mk_aabs (vstr, body) = 

566 
S.mk_abs {Bvar = vstr, Body = body} 

567 
handle U.ERR _ => S.mk_pabs {varstruct = vstr, body = body}; 

568 

569 
fun list_mk_aabs (vstrl,tm) = 

570 
U.itlist (fn vstr => fn tm => mk_aabs(vstr,tm)) vstrl tm; 

571 

572 
fun dest_aabs used tm = 

573 
let val ({Bvar,Body}, used') = S.dest_abs used tm 

574 
in (Bvar, Body, used') end 

575 
handle U.ERR _ => 

576 
let val {varstruct, body, used} = S.dest_pabs used tm 

577 
in (varstruct, body, used) end; 

578 

579 
fun strip_aabs used tm = 

580 
let val (vstr, body, used') = dest_aabs used tm 

581 
val (bvs, core, used'') = strip_aabs used' body 

582 
in (vstr::bvs, core, used'') end 

583 
handle U.ERR _ => ([], tm, used); 

584 

585 
fun dest_combn tm 0 = (tm,[]) 

586 
 dest_combn tm n = 

587 
let val {Rator,Rand} = S.dest_comb tm 

588 
val (f,rands) = dest_combn Rator (n1) 

589 
in (f,Rand::rands) 

590 
end; 

591 

592 

593 

594 

595 
local fun dest_pair M = let val {fst,snd} = S.dest_pair M in (fst,snd) end 

596 
fun mk_fst tm = 

597 
let val ty as Type("*", [fty,sty]) = type_of tm 

598 
in Const ("fst", ty > fty) $ tm end 

599 
fun mk_snd tm = 

600 
let val ty as Type("*", [fty,sty]) = type_of tm 

601 
in Const ("snd", ty > sty) $ tm end 

602 
in 

603 
fun XFILL tych x vstruct = 

604 
let fun traverse p xocc L = 

605 
if (is_Free p) 

606 
then tych xocc::L 

607 
else let val (p1,p2) = dest_pair p 

608 
in traverse p1 (mk_fst xocc) (traverse p2 (mk_snd xocc) L) 

609 
end 

610 
in 

611 
traverse vstruct x [] 

612 
end end; 

613 

614 
(* 

615 
* Replace a free tuple (vstr) by a universally quantified variable (a). 

616 
* Note that the notion of "freeness" for a tuple is different than for a 

617 
* variable: if variables in the tuple also occur in any other place than 

618 
* an occurrences of the tuple, they aren't "free" (which is thus probably 

619 
* the wrong word to use). 

620 
**) 

621 

622 
fun VSTRUCT_ELIM tych a vstr th = 

623 
let val L = S.free_vars_lr vstr 

624 
val bind1 = tych (HOLogic.mk_Trueprop (HOLogic.mk_eq(a,vstr))) 

625 
val thm1 = implies_intr bind1 (SUBS [SYM(assume bind1)] th) 

626 
val thm2 = forall_intr_list (map tych L) thm1 

627 
val thm3 = forall_elim_list (XFILL tych a vstr) thm2 

628 
in refl RS 

629 
rewrite_rule [Thm.symmetric (surjective_pairing RS eq_reflection)] thm3 

630 
end; 

631 

632 
fun PGEN tych a vstr th = 

633 
let val a1 = tych a 

634 
val vstr1 = tych vstr 

635 
in 

636 
forall_intr a1 

637 
(if (is_Free vstr) 

638 
then cterm_instantiate [(vstr1,a1)] th 

639 
else VSTRUCT_ELIM tych a vstr th) 

640 
end; 

641 

642 

643 
(* 

644 
* Takes apart a paired betaredex, looking like "(\(x,y).N) vstr", into 

645 
* 

646 
* (([x,y],N),vstr) 

647 
**) 

648 
fun dest_pbeta_redex used M n = 

649 
let val (f,args) = dest_combn M n 

650 
val dummy = dest_aabs used f 

651 
in (strip_aabs used f,args) 

652 
end; 

653 

654 
fun pbeta_redex M n = can (U.C (dest_pbeta_redex []) n) M; 

655 

656 
fun dest_impl tm = 

657 
let val ants = Logic.strip_imp_prems tm 

658 
val eq = Logic.strip_imp_concl tm 

659 
in (ants,get_lhs eq) 

660 
end; 

661 

15570  662 
fun restricted t = isSome (S.find_term 
10769  663 
(fn (Const("Wellfounded_Recursion.cut",_)) =>true  _ => false) 
664 
t) 

665 

666 
fun CONTEXT_REWRITE_RULE (func, G, cut_lemma, congs) th = 

667 
let val globals = func::G 

10918  668 
val pbeta_reduce = simpl_conv empty_ss [split_conv RS eq_reflection]; 
10769  669 
val tc_list = ref[]: term list ref 
670 
val dummy = term_ref := [] 

671 
val dummy = thm_ref := [] 

15021  672 
val dummy = ss_ref := [] 
10769  673 
val cut_lemma' = cut_lemma RS eq_reflection 
15021  674 
fun prover used ss thm = 
675 
let fun cong_prover ss thm = 

10769  676 
let val dummy = say "cong_prover:" 
15021  677 
val cntxt = MetaSimplifier.prems_of_ss ss 
10769  678 
val dummy = print_thms "cntxt:" cntxt 
679 
val dummy = say "cong rule:" 

680 
val dummy = say (string_of_thm thm) 

681 
val dummy = thm_ref := (thm :: !thm_ref) 

15021  682 
val dummy = ss_ref := (ss :: !ss_ref) 
10769  683 
(* Unquantified eliminate *) 
684 
fun uq_eliminate (thm,imp,sign) = 

685 
let val tych = cterm_of sign 

686 
val dummy = print_cterms "To eliminate:" [tych imp] 

687 
val ants = map tych (Logic.strip_imp_prems imp) 

688 
val eq = Logic.strip_imp_concl imp 

689 
val lhs = tych(get_lhs eq) 

15021  690 
val ss' = MetaSimplifier.add_prems (map ASSUME ants) ss 
691 
val lhs_eq_lhs1 = MetaSimplifier.rewrite_cterm (false,true,false) (prover used) ss' lhs 

10769  692 
handle U.ERR _ => Thm.reflexive lhs 
693 
val dummy = print_thms "proven:" [lhs_eq_lhs1] 

694 
val lhs_eq_lhs2 = implies_intr_list ants lhs_eq_lhs1 

695 
val lhs_eeq_lhs2 = lhs_eq_lhs2 RS meta_eq_to_obj_eq 

696 
in 

697 
lhs_eeq_lhs2 COMP thm 

698 
end 

699 
fun pq_eliminate (thm,sign,vlist,imp_body,lhs_eq) = 

700 
let val ((vstrl, _, used'), args) = dest_pbeta_redex used lhs_eq (length vlist) 

701 
val dummy = assert (forall (op aconv) 

702 
(ListPair.zip (vlist, args))) 

703 
"assertion failed in CONTEXT_REWRITE_RULE" 

704 
val imp_body1 = subst_free (ListPair.zip (args, vstrl)) 

705 
imp_body 

706 
val tych = cterm_of sign 

707 
val ants1 = map tych (Logic.strip_imp_prems imp_body1) 

708 
val eq1 = Logic.strip_imp_concl imp_body1 

709 
val Q = get_lhs eq1 

710 
val QeqQ1 = pbeta_reduce (tych Q) 

711 
val Q1 = #2(D.dest_eq(cconcl QeqQ1)) 

15021  712 
val ss' = MetaSimplifier.add_prems (map ASSUME ants1) ss 
713 
val Q1eeqQ2 = MetaSimplifier.rewrite_cterm (false,true,false) (prover used') ss' Q1 

10769  714 
handle U.ERR _ => Thm.reflexive Q1 
14643  715 
val Q2 = #2 (Logic.dest_equals (Thm.prop_of Q1eeqQ2)) 
10769  716 
val Q3 = tych(list_comb(list_mk_aabs(vstrl,Q2),vstrl)) 
717 
val Q2eeqQ3 = Thm.symmetric(pbeta_reduce Q3 RS eq_reflection) 

718 
val thA = Thm.transitive(QeqQ1 RS eq_reflection) Q1eeqQ2 

719 
val QeeqQ3 = Thm.transitive thA Q2eeqQ3 handle THM _ => 

720 
((Q2eeqQ3 RS meta_eq_to_obj_eq) 

721 
RS ((thA RS meta_eq_to_obj_eq) RS trans)) 

722 
RS eq_reflection 

723 
val impth = implies_intr_list ants1 QeeqQ3 

724 
val impth1 = impth RS meta_eq_to_obj_eq 

725 
(* Need to abstract *) 

726 
val ant_th = U.itlist2 (PGEN tych) args vstrl impth1 

727 
in ant_th COMP thm 

728 
end 

729 
fun q_eliminate (thm,imp,sign) = 

730 
let val (vlist, imp_body, used') = strip_all used imp 

731 
val (ants,Q) = dest_impl imp_body 

732 
in if (pbeta_redex Q) (length vlist) 

733 
then pq_eliminate (thm,sign,vlist,imp_body,Q) 

734 
else 

735 
let val tych = cterm_of sign 

736 
val ants1 = map tych ants 

15021  737 
val ss' = MetaSimplifier.add_prems (map ASSUME ants1) ss 
10769  738 
val Q_eeq_Q1 = MetaSimplifier.rewrite_cterm 
15021  739 
(false,true,false) (prover used') ss' (tych Q) 
10769  740 
handle U.ERR _ => Thm.reflexive (tych Q) 
741 
val lhs_eeq_lhs2 = implies_intr_list ants1 Q_eeq_Q1 

742 
val lhs_eq_lhs2 = lhs_eeq_lhs2 RS meta_eq_to_obj_eq 

743 
val ant_th = forall_intr_list(map tych vlist)lhs_eq_lhs2 

744 
in 

745 
ant_th COMP thm 

746 
end end 

747 

748 
fun eliminate thm = 

749 
case (rep_thm thm) 

750 
of {prop = (Const("==>",_) $ imp $ _), sign, ...} => 

751 
eliminate 

752 
(if not(is_all imp) 

753 
then uq_eliminate (thm,imp,sign) 

754 
else q_eliminate (thm,imp,sign)) 

755 
(* Assume that the leading constant is ==, *) 

756 
 _ => thm (* if it is not a ==> *) 

15531  757 
in SOME(eliminate (rename thm)) end 
758 
handle U.ERR _ => NONE (* FIXME handle THM as well?? *) 

10769  759 

15021  760 
fun restrict_prover ss thm = 
10769  761 
let val dummy = say "restrict_prover:" 
15021  762 
val cntxt = rev(MetaSimplifier.prems_of_ss ss) 
10769  763 
val dummy = print_thms "cntxt:" cntxt 
764 
val {prop = Const("==>",_) $ (Const("Trueprop",_) $ A) $ _, 

765 
sign,...} = rep_thm thm 

766 
fun genl tm = let val vlist = gen_rems (op aconv) 

767 
(add_term_frees(tm,[]), globals) 

768 
in U.itlist Forall vlist tm 

769 
end 

770 
(* 

771 
* This actually isn't quite right, since it will think that 

772 
* notfully applied occs. of "f" in the context mean that the 

773 
* current call is nested. The real solution is to pass in a 

774 
* term "f v1..vn" which is a pattern that any full application 

775 
* of "f" will match. 

776 
**) 

777 
val func_name = #1(dest_Const func) 

778 
fun is_func (Const (name,_)) = (name = func_name) 

779 
 is_func _ = false 

780 
val rcontext = rev cntxt 

14643  781 
val cncl = HOLogic.dest_Trueprop o Thm.prop_of 
10769  782 
val antl = case rcontext of [] => [] 
783 
 _ => [S.list_mk_conj(map cncl rcontext)] 

784 
val TC = genl(S.list_mk_imp(antl, A)) 

785 
val dummy = print_cterms "func:" [cterm_of sign func] 

786 
val dummy = print_cterms "TC:" 

787 
[cterm_of sign (HOLogic.mk_Trueprop TC)] 

788 
val dummy = tc_list := (TC :: !tc_list) 

15570  789 
val nestedp = isSome (S.find_term is_func TC) 
10769  790 
val dummy = if nestedp then say "nested" else say "not_nested" 
791 
val dummy = term_ref := ([func,TC]@(!term_ref)) 

792 
val th' = if nestedp then raise RULES_ERR "solver" "nested function" 

793 
else let val cTC = cterm_of sign 

794 
(HOLogic.mk_Trueprop TC) 

795 
in case rcontext of 

796 
[] => SPEC_ALL(ASSUME cTC) 

797 
 _ => MP (SPEC_ALL (ASSUME cTC)) 

798 
(LIST_CONJ rcontext) 

799 
end 

800 
val th'' = th' RS thm 

15531  801 
in SOME (th'') 
802 
end handle U.ERR _ => NONE (* FIXME handle THM as well?? *) 

10769  803 
in 
15021  804 
(if (is_cong thm) then cong_prover else restrict_prover) ss thm 
10769  805 
end 
806 
val ctm = cprop_of th 

807 
val names = add_term_names (term_of ctm, []) 

808 
val th1 = MetaSimplifier.rewrite_cterm(false,true,false) 

15021  809 
(prover names) (empty_ss addsimps [cut_lemma'] addeqcongs congs) ctm 
10769  810 
val th2 = equal_elim th1 th 
811 
in 

15570  812 
(th2, List.filter (not o restricted) (!tc_list)) 
10769  813 
end; 
814 

815 

11632  816 
fun prove strict (ptm, tac) = 
10769  817 
let val result = 
11632  818 
if strict then Goals.prove_goalw_cterm [] ptm (fn _ => [tac]) 
819 
else 

14836  820 
transform_error (fn () => 
11632  821 
Goals.prove_goalw_cterm [] ptm (fn _ => [tac])) () 
822 
handle ERROR_MESSAGE msg => (warning msg; raise RULES_ERR "prove" msg); 

10769  823 
in #1 (freeze_thaw result) end; 
824 

825 

826 
end; 