author | clasohm |
Tue, 30 Jan 1996 13:42:57 +0100 | |
changeset 1461 | 6bcb44e4d6e5 |
parent 782 | 200a16083201 |
child 2469 | b50b8c0eec01 |
permissions | -rw-r--r-- |
1461 | 1 |
(* Title: ZF/trancl.ML |
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ID: $Id$ |
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Author: Lawrence C Paulson, Cambridge University Computer Laboratory |
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Copyright 1992 University of Cambridge |
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For trancl.thy. Transitive closure of a relation |
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*) |
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open Trancl; |
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goal Trancl.thy "bnd_mono(field(r)*field(r), %s. id(field(r)) Un (r O s))"; |
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by (rtac bnd_monoI 1); |
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by (REPEAT (ares_tac [subset_refl, Un_mono, comp_mono] 2)); |
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by (fast_tac comp_cs 1); |
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qed "rtrancl_bnd_mono"; |
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val [prem] = goalw Trancl.thy [rtrancl_def] "r<=s ==> r^* <= s^*"; |
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by (rtac lfp_mono 1); |
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by (REPEAT (resolve_tac [rtrancl_bnd_mono, prem, subset_refl, id_mono, |
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comp_mono, Un_mono, field_mono, Sigma_mono] 1)); |
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qed "rtrancl_mono"; |
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(* r^* = id(field(r)) Un ( r O r^* ) *) |
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val rtrancl_unfold = rtrancl_bnd_mono RS (rtrancl_def RS def_lfp_Tarski); |
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(** The relation rtrancl **) |
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200a16083201
added bind_thm for theorems defined by "standard ..."
clasohm
parents:
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changeset
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bind_thm ("rtrancl_type", (rtrancl_def RS def_lfp_subset)); |
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(*Reflexivity of rtrancl*) |
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val [prem] = goal Trancl.thy "[| a: field(r) |] ==> <a,a> : r^*"; |
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by (resolve_tac [rtrancl_unfold RS ssubst] 1); |
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by (rtac (prem RS idI RS UnI1) 1); |
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qed "rtrancl_refl"; |
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(*Closure under composition with r *) |
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val prems = goal Trancl.thy |
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"[| <a,b> : r^*; <b,c> : r |] ==> <a,c> : r^*"; |
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by (resolve_tac [rtrancl_unfold RS ssubst] 1); |
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by (rtac (compI RS UnI2) 1); |
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by (resolve_tac prems 1); |
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by (resolve_tac prems 1); |
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qed "rtrancl_into_rtrancl"; |
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(*rtrancl of r contains all pairs in r *) |
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val prems = goal Trancl.thy "<a,b> : r ==> <a,b> : r^*"; |
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by (resolve_tac [rtrancl_refl RS rtrancl_into_rtrancl] 1); |
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by (REPEAT (resolve_tac (prems@[fieldI1]) 1)); |
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qed "r_into_rtrancl"; |
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(*The premise ensures that r consists entirely of pairs*) |
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val prems = goal Trancl.thy "r <= Sigma(A,B) ==> r <= r^*"; |
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by (cut_facts_tac prems 1); |
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by (fast_tac (ZF_cs addIs [r_into_rtrancl]) 1); |
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qed "r_subset_rtrancl"; |
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goal Trancl.thy "field(r^*) = field(r)"; |
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by (fast_tac (eq_cs addIs [r_into_rtrancl] |
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addSDs [rtrancl_type RS subsetD]) 1); |
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qed "rtrancl_field"; |
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(** standard induction rule **) |
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val major::prems = goal Trancl.thy |
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"[| <a,b> : r^*; \ |
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\ !!x. x: field(r) ==> P(<x,x>); \ |
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\ !!x y z.[| P(<x,y>); <x,y>: r^*; <y,z>: r |] ==> P(<x,z>) |] \ |
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\ ==> P(<a,b>)"; |
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by (rtac ([rtrancl_def, rtrancl_bnd_mono, major] MRS def_induct) 1); |
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by (fast_tac (ZF_cs addIs prems addSEs [idE,compE]) 1); |
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qed "rtrancl_full_induct"; |
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(*nice induction rule. |
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Tried adding the typing hypotheses y,z:field(r), but these |
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caused expensive case splits!*) |
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val major::prems = goal Trancl.thy |
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"[| <a,b> : r^*; \ |
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\ P(a); \ |
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\ !!y z.[| <a,y> : r^*; <y,z> : r; P(y) |] ==> P(z) \ |
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\ |] ==> P(b)"; |
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(*by induction on this formula*) |
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by (subgoal_tac "ALL y. <a,b> = <a,y> --> P(y)" 1); |
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(*now solve first subgoal: this formula is sufficient*) |
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by (EVERY1 [etac (spec RS mp), rtac refl]); |
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(*now do the induction*) |
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by (resolve_tac [major RS rtrancl_full_induct] 1); |
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by (ALLGOALS (fast_tac (ZF_cs addIs prems))); |
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qed "rtrancl_induct"; |
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(*transitivity of transitive closure!! -- by induction.*) |
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goalw Trancl.thy [trans_def] "trans(r^*)"; |
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by (REPEAT (resolve_tac [allI,impI] 1)); |
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by (eres_inst_tac [("b","z")] rtrancl_induct 1); |
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by (DEPTH_SOLVE (eresolve_tac [asm_rl, rtrancl_into_rtrancl] 1)); |
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qed "trans_rtrancl"; |
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(*elimination of rtrancl -- by induction on a special formula*) |
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val major::prems = goal Trancl.thy |
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"[| <a,b> : r^*; (a=b) ==> P; \ |
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\ !!y.[| <a,y> : r^*; <y,b> : r |] ==> P |] \ |
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\ ==> P"; |
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by (subgoal_tac "a = b | (EX y. <a,y> : r^* & <y,b> : r)" 1); |
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(*see HOL/trancl*) |
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by (rtac (major RS rtrancl_induct) 2); |
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by (ALLGOALS (fast_tac (ZF_cs addSEs prems))); |
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qed "rtranclE"; |
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(**** The relation trancl ****) |
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(*Transitivity of r^+ is proved by transitivity of r^* *) |
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goalw Trancl.thy [trans_def,trancl_def] "trans(r^+)"; |
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by (safe_tac comp_cs); |
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by (rtac (rtrancl_into_rtrancl RS (trans_rtrancl RS transD RS compI)) 1); |
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by (REPEAT (assume_tac 1)); |
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qed "trans_trancl"; |
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(** Conversions between trancl and rtrancl **) |
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val [major] = goalw Trancl.thy [trancl_def] "<a,b> : r^+ ==> <a,b> : r^*"; |
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by (resolve_tac [major RS compEpair] 1); |
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by (REPEAT (ares_tac [rtrancl_into_rtrancl] 1)); |
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qed "trancl_into_rtrancl"; |
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(*r^+ contains all pairs in r *) |
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val [prem] = goalw Trancl.thy [trancl_def] "<a,b> : r ==> <a,b> : r^+"; |
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by (REPEAT (ares_tac [prem,compI,rtrancl_refl,fieldI1] 1)); |
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qed "r_into_trancl"; |
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(*The premise ensures that r consists entirely of pairs*) |
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val prems = goal Trancl.thy "r <= Sigma(A,B) ==> r <= r^+"; |
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by (cut_facts_tac prems 1); |
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by (fast_tac (ZF_cs addIs [r_into_trancl]) 1); |
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qed "r_subset_trancl"; |
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(*intro rule by definition: from r^* and r *) |
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val prems = goalw Trancl.thy [trancl_def] |
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"[| <a,b> : r^*; <b,c> : r |] ==> <a,c> : r^+"; |
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by (REPEAT (resolve_tac ([compI]@prems) 1)); |
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qed "rtrancl_into_trancl1"; |
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(*intro rule from r and r^* *) |
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val prems = goal Trancl.thy |
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"[| <a,b> : r; <b,c> : r^* |] ==> <a,c> : r^+"; |
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by (resolve_tac (prems RL [rtrancl_induct]) 1); |
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by (resolve_tac (prems RL [r_into_trancl]) 1); |
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by (etac (trans_trancl RS transD) 1); |
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by (etac r_into_trancl 1); |
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qed "rtrancl_into_trancl2"; |
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(*Nice induction rule for trancl*) |
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val major::prems = goal Trancl.thy |
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"[| <a,b> : r^+; \ |
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\ !!y. [| <a,y> : r |] ==> P(y); \ |
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\ !!y z.[| <a,y> : r^+; <y,z> : r; P(y) |] ==> P(z) \ |
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\ |] ==> P(b)"; |
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by (rtac (rewrite_rule [trancl_def] major RS compEpair) 1); |
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(*by induction on this formula*) |
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by (subgoal_tac "ALL z. <y,z> : r --> P(z)" 1); |
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(*now solve first subgoal: this formula is sufficient*) |
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by (fast_tac ZF_cs 1); |
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by (etac rtrancl_induct 1); |
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by (ALLGOALS (fast_tac (ZF_cs addIs (rtrancl_into_trancl1::prems)))); |
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qed "trancl_induct"; |
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(*elimination of r^+ -- NOT an induction rule*) |
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val major::prems = goal Trancl.thy |
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"[| <a,b> : r^+; \ |
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\ <a,b> : r ==> P; \ |
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\ !!y.[| <a,y> : r^+; <y,b> : r |] ==> P \ |
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\ |] ==> P"; |
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by (subgoal_tac "<a,b> : r | (EX y. <a,y> : r^+ & <y,b> : r)" 1); |
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by (fast_tac (ZF_cs addIs prems) 1); |
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by (rtac (rewrite_rule [trancl_def] major RS compEpair) 1); |
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by (etac rtranclE 1); |
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by (ALLGOALS (fast_tac (ZF_cs addIs [rtrancl_into_trancl1]))); |
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qed "tranclE"; |
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goalw Trancl.thy [trancl_def] "r^+ <= field(r)*field(r)"; |
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by (fast_tac (ZF_cs addEs [compE, rtrancl_type RS subsetD RS SigmaE2]) 1); |
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qed "trancl_type"; |
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val [prem] = goalw Trancl.thy [trancl_def] "r<=s ==> r^+ <= s^+"; |
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by (REPEAT (resolve_tac [prem, comp_mono, rtrancl_mono] 1)); |
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qed "trancl_mono"; |
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