# HG changeset patch # User wenzelm # Date 972656721 -7200 # Node ID a5653826379ed33838ebb1917ce75eaae0125262 # Parent c0cfc4ac12e29591b5abc83db4d8dbf9383713c0 back to 1.167, due to Emacs/CVS casualty!!; diff -r c0cfc4ac12e2 -r a5653826379e src/Pure/thm.ML --- a/src/Pure/thm.ML Fri Oct 27 15:53:47 2000 +0200 +++ b/src/Pure/thm.ML Fri Oct 27 16:25:21 2000 +0200 @@ -28,15 +28,10 @@ val read_cterm : Sign.sg -> string * typ -> cterm val cterm_fun : (term -> term) -> (cterm -> cterm) val dest_comb : cterm -> cterm * cterm - val dest_abs : string option -> cterm -> cterm * cterm + val dest_abs : cterm -> cterm * cterm val adjust_maxidx : cterm -> cterm val capply : cterm -> cterm -> cterm val cabs : cterm -> cterm -> cterm - val cterm_match : cterm * cterm -> - (indexname * ctyp) list * (cterm * cterm) list - val cterm_first_order_match : cterm * cterm -> - (indexname * ctyp) list * (cterm * cterm) list - val cterm_incr_indexes : int -> cterm -> cterm val read_def_cterm : Sign.sg * (indexname -> typ option) * (indexname -> sort option) -> string list -> bool -> string * typ -> cterm * (indexname * typ) list @@ -64,7 +59,6 @@ | Symmetric | Transitive | Beta_conversion of cterm - | Eta_conversion of cterm | Extensional | Abstract_rule of string * cterm | Combination @@ -123,8 +117,7 @@ val reflexive : cterm -> thm val symmetric : thm -> thm val transitive : thm -> thm -> thm - val beta_conversion : bool -> cterm -> thm - val eta_conversion : cterm -> thm + val beta_conversion : cterm -> thm val extensional : thm -> thm val abstract_rule : string -> cterm -> thm -> thm val combination : thm -> thm -> thm @@ -142,7 +135,6 @@ val dest_state : thm * int -> (term * term) list * term list * term * term val lift_rule : (thm * int) -> thm -> thm -(* val incr_indexes : int -> thm -> thm*) val assumption : int -> thm -> thm Seq.seq val eq_assumption : int -> thm -> thm val rotate_rule : int -> int -> thm -> thm @@ -152,6 +144,37 @@ int -> thm -> thm Seq.seq val biresolution : bool -> (bool * thm) list -> int -> thm -> thm Seq.seq + + (*meta simplification*) + exception SIMPLIFIER of string * thm + type meta_simpset + val dest_mss : meta_simpset -> + {simps: thm list, congs: thm list, procs: (string * cterm list) list} + val empty_mss : meta_simpset + val clear_mss : meta_simpset -> meta_simpset + val merge_mss : meta_simpset * meta_simpset -> meta_simpset + val add_simps : meta_simpset * thm list -> meta_simpset + val del_simps : meta_simpset * thm list -> meta_simpset + val mss_of : thm list -> meta_simpset + val add_congs : meta_simpset * thm list -> meta_simpset + val del_congs : meta_simpset * thm list -> meta_simpset + val add_simprocs : meta_simpset * + (string * cterm list * (Sign.sg -> thm list -> term -> thm option) * stamp) list + -> meta_simpset + val del_simprocs : meta_simpset * + (string * cterm list * (Sign.sg -> thm list -> term -> thm option) * stamp) list + -> meta_simpset + val add_prems : meta_simpset * thm list -> meta_simpset + val prems_of_mss : meta_simpset -> thm list + val set_mk_rews : meta_simpset * (thm -> thm list) -> meta_simpset + val set_mk_sym : meta_simpset * (thm -> thm option) -> meta_simpset + val set_mk_eq_True : meta_simpset * (thm -> thm option) -> meta_simpset + val set_termless : meta_simpset * (term * term -> bool) -> meta_simpset + val trace_simp : bool ref + val debug_simp : bool ref + val rewrite_cterm : bool * bool * bool -> meta_simpset -> + (meta_simpset -> thm -> thm option) -> cterm -> thm + val invoke_oracle : theory -> xstring -> Sign.sg * Object.T -> thm end; @@ -168,11 +191,6 @@ val name_of_thm : thm -> string val tags_of_thm : thm -> tag list val name_thm : string * thm -> thm - val match_bvs : term * term * (string * string) list -> (string * string) list - val add_typ_sorts : typ * sort list -> sort list - val add_typs_sorts : typ list * sort list -> sort list - val add_term_sorts : term * sort list -> sort list - val add_terms_sorts : term list * sort list -> sort list end; structure Thm: THM = @@ -240,12 +258,12 @@ | dest_comb _ = raise CTERM "dest_comb"; (*Destruct abstraction in cterms*) -fun dest_abs a (Cterm {sign_ref, T as Type("fun",[_,S]), maxidx, t=Abs(x,ty,M)}) = - let val (y,N) = variant_abs (if_none a x,ty,M) +fun dest_abs (Cterm {sign_ref, T as Type("fun",[_,S]), maxidx, t=Abs(x,ty,M)}) = + let val (y,N) = variant_abs (x,ty,M) in (Cterm {sign_ref = sign_ref, T = ty, maxidx = 0, t = Free(y,ty)}, Cterm {sign_ref = sign_ref, T = S, maxidx = maxidx, t = N}) end - | dest_abs _ _ = raise CTERM "dest_abs"; + | dest_abs _ = raise CTERM "dest_abs"; (*Makes maxidx precise: it is often too big*) fun adjust_maxidx (ct as Cterm {sign_ref, T, t, maxidx, ...}) = @@ -267,33 +285,6 @@ T = ty --> T2, maxidx=Int.max(maxidx1, maxidx2)} | cabs _ _ = raise CTERM "cabs: first arg is not a free variable"; -(*Matching of cterms*) -fun gen_cterm_match mtch - (Cterm {sign_ref = sign_ref1, maxidx = maxidx1, t = t1, ...}, - Cterm {sign_ref = sign_ref2, maxidx = maxidx2, t = t2, ...}) = - let - val sign_ref = Sign.merge_refs (sign_ref1, sign_ref2); - val tsig = Sign.tsig_of (Sign.deref sign_ref); - val (Tinsts, tinsts) = mtch tsig (t1, t2); - val maxidx = Int.max (maxidx1, maxidx2); - val vars = map dest_Var (term_vars t1); - fun mk_cTinsts (ixn, T) = (ixn, Ctyp {sign_ref = sign_ref, T = T}); - fun mk_ctinsts (ixn, t) = - let val T = typ_subst_TVars Tinsts (the (assoc (vars, ixn))) - in - (Cterm {sign_ref = sign_ref, maxidx = maxidx, T = T, t = Var (ixn, T)}, - Cterm {sign_ref = sign_ref, maxidx = maxidx, T = T, t = t}) - end; - in (map mk_cTinsts Tinsts, map mk_ctinsts tinsts) end; - -val cterm_match = gen_cterm_match Pattern.match; -val cterm_first_order_match = gen_cterm_match Pattern.first_order_match; - -(*Incrementing indexes*) -fun cterm_incr_indexes i (Cterm {sign_ref, maxidx, t, T}) = - Cterm {sign_ref = sign_ref, maxidx = maxidx + i, - t = Logic.incr_indexes ([], i) t, T = Term.incr_tvar i T}; - (** read cterms **) (*exception ERROR*) @@ -340,7 +331,6 @@ | Symmetric | Transitive | Beta_conversion of cterm - | Eta_conversion of cterm | Extensional | Abstract_rule of string * cterm | Combination @@ -538,9 +528,6 @@ Vartab.foldl (add_term_sorts o swap o apsnd snd) (Vartab.foldl (add_typ_sorts o swap o apsnd snd) (Ss, iTs), asol); -fun add_insts_sorts ((iTs, is), Ss) = - add_typs_sorts (map snd iTs, add_terms_sorts (map snd is, Ss)); - fun add_thm_sorts (Thm {hyps, prop, ...}, Ss) = add_terms_sorts (hyps, add_term_sorts (prop, Ss)); @@ -707,17 +694,17 @@ ------- A ==> B *) -fun implies_intr cA (thB as Thm{sign_ref,der,maxidx,hyps,shyps,prop}) : thm = +fun implies_intr cA (thB as Thm{sign_ref,der,maxidx,hyps,prop,...}) : thm = let val Cterm {sign_ref=sign_refA, t=A, T, maxidx=maxidxA} = cA in if T<>propT then raise THM("implies_intr: assumptions must have type prop", 0, [thB]) - else - Thm{sign_ref = Sign.merge_refs (sign_ref,sign_refA), + else fix_shyps [thB] [] + (Thm{sign_ref = Sign.merge_refs (sign_ref,sign_refA), der = infer_derivs (Implies_intr cA, [der]), maxidx = Int.max(maxidxA, maxidx), - shyps = add_term_sorts (A, shyps), + shyps = [], hyps = disch(hyps,A), - prop = implies$A$prop} + prop = implies$A$prop}) handle TERM _ => raise THM("implies_intr: incompatible signatures", 0, [thB]) end; @@ -729,19 +716,19 @@ B *) fun implies_elim thAB thA : thm = - let val Thm{maxidx=maxA, der=derA, hyps=hypsA, shyps=shypsA, prop=propA, ...} = thA - and Thm{der, maxidx, hyps, shyps, prop, ...} = thAB; + let val Thm{maxidx=maxA, der=derA, hyps=hypsA, prop=propA,...} = thA + and Thm{sign_ref, der, maxidx, hyps, prop,...} = thAB; fun err(a) = raise THM("implies_elim: "^a, 0, [thAB,thA]) in case prop of imp$A$B => if imp=implies andalso A aconv propA - then - Thm{sign_ref= merge_thm_sgs(thAB,thA), - der = infer_derivs (Implies_elim, [der,derA]), - maxidx = Int.max(maxA,maxidx), - shyps = union_sort (shypsA, shyps), - hyps = union_term(hypsA,hyps), (*dups suppressed*) - prop = B} + then fix_shyps [thAB, thA] [] + (Thm{sign_ref= merge_thm_sgs(thAB,thA), + der = infer_derivs (Implies_elim, [der,derA]), + maxidx = Int.max(maxA,maxidx), + shyps = [], + hyps = union_term(hypsA,hyps), (*dups suppressed*) + prop = B}) else err("major premise") | _ => err("major premise") end; @@ -834,19 +821,20 @@ t1==t2 *) fun transitive th1 th2 = - let val Thm{der=der1, maxidx=max1, hyps=hyps1, shyps=shyps1, prop=prop1,...} = th1 - and Thm{der=der2, maxidx=max2, hyps=hyps2, shyps=shyps2, prop=prop2,...} = th2; + let val Thm{der=der1, maxidx=max1, hyps=hyps1, prop=prop1,...} = th1 + and Thm{der=der2, maxidx=max2, hyps=hyps2, prop=prop2,...} = th2; fun err(msg) = raise THM("transitive: "^msg, 0, [th1,th2]) in case (prop1,prop2) of ((eq as Const("==",_)) $ t1 $ u, Const("==",_) $ u' $ t2) => if not (u aconv u') then err"middle term" else let val thm = - Thm{sign_ref= merge_thm_sgs(th1,th2), + fix_shyps [th1, th2] [] + (Thm{sign_ref= merge_thm_sgs(th1,th2), der = infer_derivs (Transitive, [der1, der2]), maxidx = Int.max(max1,max2), - shyps = union_sort (shyps1, shyps2), + shyps = [], hyps = union_term(hyps1,hyps2), - prop = eq$t1$t2} + prop = eq$t1$t2}) in if max1 >= 0 andalso max2 >= 0 then nodup_vars thm "transitive" else thm (*no new Vars: no expensive check!*) @@ -854,32 +842,18 @@ | _ => err"premises" end; -(*Beta-conversion: maps (%x.t)(u) to the theorem (%x.t)(u) == t[u/x] - Fully beta-reduces the term if full=true -*) -fun beta_conversion full ct = +(*Beta-conversion: maps (%x.t)(u) to the theorem (%x.t)(u) == t[u/x] *) +fun beta_conversion ct = let val Cterm {sign_ref, t, T, maxidx} = ct - in fix_shyps [] [] (Thm - {sign_ref = sign_ref, - der = infer_derivs (Beta_conversion ct, []), - maxidx = maxidx, - shyps = [], - hyps = [], - prop = Logic.mk_equals (t, if full then Envir.norm_term (Envir.empty 0) t - else case t of - Abs(_, _, bodt) $ u => subst_bound (u, bodt) - | _ => raise THM ("beta_conversion: not a redex", 0, []))}) - end; - -fun eta_conversion ct = - let val Cterm {sign_ref, t, T, maxidx} = ct - in fix_shyps [] [] (Thm - {sign_ref = sign_ref, - der = infer_derivs (Eta_conversion ct, []), - maxidx = maxidx, - shyps = [], - hyps = [], - prop = Logic.mk_equals (t, Pattern.eta_contract t)}) + in case t of + Abs(_,_,bodt) $ u => fix_shyps [] [] + (Thm{sign_ref = sign_ref, + der = infer_derivs (Beta_conversion ct, []), + maxidx = maxidx, + shyps = [], + hyps = [], + prop = Logic.mk_equals(t, subst_bound (u,bodt))}) + | _ => raise THM("beta_conversion: not a redex", 0, []) end; (*The extensionality rule (proviso: x not free in f, g, or hypotheses) @@ -916,19 +890,19 @@ ------------ %x.t == %x.u *) -fun abstract_rule a cx (th as Thm{sign_ref,der,maxidx,hyps,shyps,prop}) = +fun abstract_rule a cx (th as Thm{sign_ref,der,maxidx,hyps,prop,...}) = let val x = term_of cx; val (t,u) = Logic.dest_equals prop handle TERM _ => raise THM("abstract_rule: premise not an equality", 0, [th]) - fun result T = - Thm{sign_ref = sign_ref, + fun result T = fix_shyps [th] [] + (Thm{sign_ref = sign_ref, der = infer_derivs (Abstract_rule (a,cx), [der]), maxidx = maxidx, - shyps = add_typ_sorts (T, shyps), + shyps = [], hyps = hyps, prop = Logic.mk_equals(Abs(a, T, abstract_over (x,t)), - Abs(a, T, abstract_over (x,u)))} + Abs(a, T, abstract_over (x,u)))}) in case x of Free(_,T) => if exists (apl(x, Logic.occs)) hyps @@ -948,18 +922,17 @@ prop=prop1,...} = th1 and Thm{der=der2, maxidx=max2, shyps=shyps2, hyps=hyps2, prop=prop2,...} = th2 - fun chktypes fT tT = - (case fT of + fun chktypes (f,t) = + (case fastype_of f of Type("fun",[T1,T2]) => - if T1 <> tT then + if T1 <> fastype_of t then raise THM("combination: types", 0, [th1,th2]) else () | _ => raise THM("combination: not function type", 0, [th1,th2])) in case (prop1,prop2) of - (Const ("==", Type ("fun", [fT, _])) $ f $ g, - Const ("==", Type ("fun", [tT, _])) $ t $ u) => - let val _ = chktypes fT tT + (Const("==",_) $ f $ g, Const("==",_) $ t $ u) => + let val _ = chktypes (f,t) val thm = (*no fix_shyps*) Thm{sign_ref = merge_thm_sgs(th1,th2), der = infer_derivs (Combination, [der1, der2]), @@ -1105,19 +1078,20 @@ Instantiates distinct Vars by terms of same type. No longer normalizes the new theorem! *) fun instantiate ([], []) th = th - | instantiate (vcTs,ctpairs) (th as Thm{sign_ref,der,maxidx,hyps,shyps,prop}) = + | instantiate (vcTs,ctpairs) (th as Thm{sign_ref,der,maxidx,hyps,prop,...}) = let val (newsign_ref,tpairs) = foldr add_ctpair (ctpairs, (sign_ref,[])); val (newsign_ref,vTs) = foldr add_ctyp (vcTs, (newsign_ref,[])); val newprop = subst_atomic tpairs (Type.inst_term_tvars (Sign.tsig_of (Sign.deref newsign_ref),vTs) prop) val newth = - (Thm{sign_ref = newsign_ref, - der = infer_derivs (Instantiate(vcTs,ctpairs), [der]), - maxidx = maxidx_of_term newprop, - shyps = add_insts_sorts ((vTs, tpairs), shyps), - hyps = hyps, - prop = newprop}) + fix_shyps [th] (map snd vTs) + (Thm{sign_ref = newsign_ref, + der = infer_derivs (Instantiate(vcTs,ctpairs), [der]), + maxidx = maxidx_of_term newprop, + shyps = [], + hyps = hyps, + prop = newprop}) in if not(instl_ok(map #1 tpairs)) then raise THM("instantiate: variables not distinct", 0, [th]) else if not(null(findrep(map #1 vTs))) @@ -1223,16 +1197,6 @@ lift_all B)} end; -(* -fun incr_indexes i (Thm {sign_ref, der, maxidx, shyps, hyps, prop}) = - Thm {sign_ref = sign_ref, - der = der, - maxidx = maxidx + i, - shyps = shyps, - hyps = hyps, - prop = Logic.incr_indexes ([], i) prop}; -*) - (*Solve subgoal Bi of proof state B1...Bn/C by assumption. *) fun assumption i state = let val Thm{sign_ref,der,maxidx,hyps,prop,...} = state; @@ -1551,6 +1515,845 @@ in Seq.flat (res brules) end; + +(*** Meta Simplification ***) + +(** diagnostics **) + +exception SIMPLIFIER of string * thm; + +fun prnt warn a = if warn then warning a else writeln a; + +fun prtm warn a sign t = + (prnt warn a; prnt warn (Sign.string_of_term sign t)); + +fun prthm warn a (thm as Thm{sign_ref, prop, ...}) = + (prtm warn a (Sign.deref sign_ref) prop); + +val trace_simp = ref false; +val debug_simp = ref false; + +fun trace warn a = if !trace_simp then prnt warn a else (); +fun debug warn a = if !debug_simp then prnt warn a else (); + +fun trace_term warn a sign t = if !trace_simp then prtm warn a sign t else (); +fun debug_term warn a sign t = if !debug_simp then prtm warn a sign t else (); + +fun trace_thm warn a (thm as Thm{sign_ref, prop, ...}) = + (trace_term warn a (Sign.deref sign_ref) prop); + + + +(** meta simp sets **) + +(* basic components *) + +type rrule = {thm: thm, lhs: term, elhs: term, fo: bool, perm: bool}; +(* thm: the rewrite rule + lhs: the left-hand side + elhs: the etac-contracted lhs. + fo: use first-order matching + perm: the rewrite rule is permutative +Reamrks: + - elhs is used for matching, + lhs only for preservation of bound variable names. + - fo is set iff + either elhs is first-order (no Var is applied), + in which case fo-matching is complete, + or elhs is not a pattern, + in which case there is nothing better to do. +*) +type cong = {thm: thm, lhs: term}; +type simproc = + {name: string, proc: Sign.sg -> thm list -> term -> thm option, lhs: cterm, id: stamp}; + +fun eq_rrule ({thm = Thm {prop = p1, ...}, ...}: rrule, + {thm = Thm {prop = p2, ...}, ...}: rrule) = p1 aconv p2; + +fun eq_cong ({thm = Thm {prop = p1, ...}, ...}: cong, + {thm = Thm {prop = p2, ...}, ...}: cong) = p1 aconv p2; + +fun eq_prem (Thm {prop = p1, ...}, Thm {prop = p2, ...}) = p1 aconv p2; + +fun eq_simproc ({id = s1, ...}:simproc, {id = s2, ...}:simproc) = (s1 = s2); + +fun mk_simproc (name, proc, lhs, id) = + {name = name, proc = proc, lhs = lhs, id = id}; + + +(* datatype mss *) + +(* + A "mss" contains data needed during conversion: + rules: discrimination net of rewrite rules; + congs: association list of congruence rules and + a list of `weak' congruence constants. + A congruence is `weak' if it avoids normalization of some argument. + procs: discrimination net of simplification procedures + (functions that prove rewrite rules on the fly); + bounds: names of bound variables already used + (for generating new names when rewriting under lambda abstractions); + prems: current premises; + mk_rews: mk: turns simplification thms into rewrite rules; + mk_sym: turns == around; (needs Drule!) + mk_eq_True: turns P into P == True - logic specific; + termless: relation for ordered rewriting; +*) + +datatype meta_simpset = + Mss of { + rules: rrule Net.net, + congs: (string * cong) list * string list, + procs: simproc Net.net, + bounds: string list, + prems: thm list, + mk_rews: {mk: thm -> thm list, + mk_sym: thm -> thm option, + mk_eq_True: thm -> thm option}, + termless: term * term -> bool}; + +fun mk_mss (rules, congs, procs, bounds, prems, mk_rews, termless) = + Mss {rules = rules, congs = congs, procs = procs, bounds = bounds, + prems=prems, mk_rews=mk_rews, termless=termless}; + +fun upd_rules(Mss{rules,congs,procs,bounds,prems,mk_rews,termless}, rules') = + mk_mss(rules',congs,procs,bounds,prems,mk_rews,termless); + +val empty_mss = + let val mk_rews = {mk = K [], mk_sym = K None, mk_eq_True = K None} + in mk_mss (Net.empty, ([], []), Net.empty, [], [], mk_rews, Term.termless) end; + +fun clear_mss (Mss {mk_rews, termless, ...}) = + mk_mss (Net.empty, ([], []), Net.empty, [], [], mk_rews, termless); + + + +(** simpset operations **) + +(* term variables *) + +val add_term_varnames = foldl_aterms (fn (xs, Var (x, _)) => ins_ix (x, xs) | (xs, _) => xs); +fun term_varnames t = add_term_varnames ([], t); + + +(* dest_mss *) + +fun dest_mss (Mss {rules, congs, procs, ...}) = + {simps = map (fn (_, {thm, ...}) => thm) (Net.dest rules), + congs = map (fn (_, {thm, ...}) => thm) (fst congs), + procs = + map (fn (_, {name, lhs, id, ...}) => ((name, lhs), id)) (Net.dest procs) + |> partition_eq eq_snd + |> map (fn ps => (#1 (#1 (hd ps)), map (#2 o #1) ps)) + |> Library.sort_wrt #1}; + + +(* merge_mss *) (*NOTE: ignores mk_rews and termless of 2nd mss*) + +fun merge_mss + (Mss {rules = rules1, congs = (congs1,weak1), procs = procs1, + bounds = bounds1, prems = prems1, mk_rews, termless}, + Mss {rules = rules2, congs = (congs2,weak2), procs = procs2, + bounds = bounds2, prems = prems2, ...}) = + mk_mss + (Net.merge (rules1, rules2, eq_rrule), + (generic_merge (eq_cong o pairself snd) I I congs1 congs2, + merge_lists weak1 weak2), + Net.merge (procs1, procs2, eq_simproc), + merge_lists bounds1 bounds2, + generic_merge eq_prem I I prems1 prems2, + mk_rews, termless); + + +(* add_simps *) + +fun mk_rrule2{thm,lhs,elhs,perm} = + let val fo = Pattern.first_order elhs orelse not(Pattern.pattern elhs) + in {thm=thm,lhs=lhs,elhs=elhs,fo=fo,perm=perm} end + +fun insert_rrule(mss as Mss {rules,...}, + rrule as {thm,lhs,elhs,perm}) = + (trace_thm false "Adding rewrite rule:" thm; + let val rrule2 as {elhs,...} = mk_rrule2 rrule + val rules' = Net.insert_term ((elhs, rrule2), rules, eq_rrule) + in upd_rules(mss,rules') end + handle Net.INSERT => + (prthm true "Ignoring duplicate rewrite rule:" thm; mss)); + +fun vperm (Var _, Var _) = true + | vperm (Abs (_, _, s), Abs (_, _, t)) = vperm (s, t) + | vperm (t1 $ t2, u1 $ u2) = vperm (t1, u1) andalso vperm (t2, u2) + | vperm (t, u) = (t = u); + +fun var_perm (t, u) = + vperm (t, u) andalso eq_set (term_varnames t, term_varnames u); + +(* FIXME: it seems that the conditions on extra variables are too liberal if +prems are nonempty: does solving the prems really guarantee instantiation of +all its Vars? Better: a dynamic check each time a rule is applied. +*) +fun rewrite_rule_extra_vars prems elhs erhs = + not (term_varnames erhs subset foldl add_term_varnames (term_varnames elhs, prems)) + orelse + not ((term_tvars erhs) subset + (term_tvars elhs union List.concat(map term_tvars prems))); + +(*Simple test for looping rewrite rules and stupid orientations*) +fun reorient sign prems lhs rhs = + rewrite_rule_extra_vars prems lhs rhs + orelse + is_Var (head_of lhs) + orelse + (exists (apl (lhs, Logic.occs)) (rhs :: prems)) + orelse + (null prems andalso + Pattern.matches (#tsig (Sign.rep_sg sign)) (lhs, rhs)) + (*the condition "null prems" is necessary because conditional rewrites + with extra variables in the conditions may terminate although + the rhs is an instance of the lhs. Example: ?m < ?n ==> f(?n) == f(?m)*) + orelse + (is_Const lhs andalso not(is_Const rhs)) + +fun decomp_simp(thm as Thm {sign_ref, prop, ...}) = + let val sign = Sign.deref sign_ref; + val prems = Logic.strip_imp_prems prop; + val concl = Logic.strip_imp_concl prop; + val (lhs, rhs) = Logic.dest_equals concl handle TERM _ => + raise SIMPLIFIER ("Rewrite rule not a meta-equality", thm) + val elhs = Pattern.eta_contract lhs; + val elhs = if elhs=lhs then lhs else elhs (* try to share *) + val erhs = Pattern.eta_contract rhs; + val perm = var_perm (elhs, erhs) andalso not (elhs aconv erhs) + andalso not (is_Var elhs) + in (sign,prems,lhs,elhs,rhs,perm) end; + +fun mk_eq_True (Mss{mk_rews={mk_eq_True,...},...}) thm = + case mk_eq_True thm of + None => [] + | Some eq_True => let val (_,_,lhs,elhs,_,_) = decomp_simp eq_True + in [{thm=eq_True, lhs=lhs, elhs=elhs, perm=false}] end; + +(* create the rewrite rule and possibly also the ==True variant, + in case there are extra vars on the rhs *) +fun rrule_eq_True(thm,lhs,elhs,rhs,mss,thm2) = + let val rrule = {thm=thm, lhs=lhs, elhs=elhs, perm=false} + in if (term_varnames rhs) subset (term_varnames lhs) andalso + (term_tvars rhs) subset (term_tvars lhs) + then [rrule] + else mk_eq_True mss thm2 @ [rrule] + end; + +fun mk_rrule mss thm = + let val (_,prems,lhs,elhs,rhs,perm) = decomp_simp thm + in if perm then [{thm=thm, lhs=lhs, elhs=elhs, perm=true}] else + (* weak test for loops: *) + if rewrite_rule_extra_vars prems lhs rhs orelse + is_Var elhs + then mk_eq_True mss thm + else rrule_eq_True(thm,lhs,elhs,rhs,mss,thm) + end; + +fun orient_rrule mss thm = + let val (sign,prems,lhs,elhs,rhs,perm) = decomp_simp thm + in if perm then [{thm=thm,lhs=lhs,elhs=elhs,perm=true}] + else if reorient sign prems lhs rhs + then if reorient sign prems rhs lhs + then mk_eq_True mss thm + else let val Mss{mk_rews={mk_sym,...},...} = mss + in case mk_sym thm of + None => [] + | Some thm' => + let val (_,_,lhs',elhs',rhs',_) = decomp_simp thm' + in rrule_eq_True(thm',lhs',elhs',rhs',mss,thm) end + end + else rrule_eq_True(thm,lhs,elhs,rhs,mss,thm) + end; + +fun extract_rews(Mss{mk_rews = {mk,...},...},thms) = flat(map mk thms); + +fun orient_comb_simps comb mk_rrule (mss,thms) = + let val rews = extract_rews(mss,thms) + val rrules = flat (map mk_rrule rews) + in foldl comb (mss,rrules) end + +(* Add rewrite rules explicitly; do not reorient! *) +fun add_simps(mss,thms) = + orient_comb_simps insert_rrule (mk_rrule mss) (mss,thms); + +fun mss_of thms = + foldl insert_rrule (empty_mss, flat(map (mk_rrule empty_mss) thms)); + +fun extract_safe_rrules(mss,thm) = + flat (map (orient_rrule mss) (extract_rews(mss,[thm]))); + +fun add_safe_simp(mss,thm) = + foldl insert_rrule (mss, extract_safe_rrules(mss,thm)) + +(* del_simps *) + +fun del_rrule(mss as Mss {rules,...}, + rrule as {thm, elhs, ...}) = + (upd_rules(mss, Net.delete_term ((elhs, rrule), rules, eq_rrule)) + handle Net.DELETE => + (prthm true "Rewrite rule not in simpset:" thm; mss)); + +fun del_simps(mss,thms) = + orient_comb_simps del_rrule (map mk_rrule2 o mk_rrule mss) (mss,thms); + + +(* add_congs *) + +fun is_full_cong_prems [] varpairs = null varpairs + | is_full_cong_prems (p::prems) varpairs = + (case Logic.strip_assums_concl p of + Const("==",_) $ lhs $ rhs => + let val (x,xs) = strip_comb lhs and (y,ys) = strip_comb rhs + in is_Var x andalso forall is_Bound xs andalso + null(findrep(xs)) andalso xs=ys andalso + (x,y) mem varpairs andalso + is_full_cong_prems prems (varpairs\(x,y)) + end + | _ => false); + +fun is_full_cong (Thm{prop,...}) = +let val prems = Logic.strip_imp_prems prop + and concl = Logic.strip_imp_concl prop + val (lhs,rhs) = Logic.dest_equals concl + val (f,xs) = strip_comb lhs + and (g,ys) = strip_comb rhs +in + f=g andalso null(findrep(xs@ys)) andalso length xs = length ys andalso + is_full_cong_prems prems (xs ~~ ys) +end + +fun add_cong (Mss {rules,congs,procs,bounds,prems,mk_rews,termless}, thm) = + let + val (lhs, _) = Logic.dest_equals (concl_of thm) handle TERM _ => + raise SIMPLIFIER ("Congruence not a meta-equality", thm); +(* val lhs = Pattern.eta_contract lhs; *) + val (a, _) = dest_Const (head_of lhs) handle TERM _ => + raise SIMPLIFIER ("Congruence must start with a constant", thm); + val (alist,weak) = congs + val alist2 = overwrite_warn (alist, (a,{lhs=lhs, thm=thm})) + ("Overwriting congruence rule for " ^ quote a); + val weak2 = if is_full_cong thm then weak else a::weak + in + mk_mss (rules, (alist2,weak2), procs, bounds, prems, mk_rews, termless) + end; + +val (op add_congs) = foldl add_cong; + + +(* del_congs *) + +fun del_cong (Mss {rules,congs,procs,bounds,prems,mk_rews,termless}, thm) = + let + val (lhs, _) = Logic.dest_equals (concl_of thm) handle TERM _ => + raise SIMPLIFIER ("Congruence not a meta-equality", thm); +(* val lhs = Pattern.eta_contract lhs; *) + val (a, _) = dest_Const (head_of lhs) handle TERM _ => + raise SIMPLIFIER ("Congruence must start with a constant", thm); + val (alist,_) = congs + val alist2 = filter (fn (x,_)=> x<>a) alist + val weak2 = mapfilter (fn(a,{thm,...}) => if is_full_cong thm then None + else Some a) + alist2 + in + mk_mss (rules, (alist2,weak2), procs, bounds, prems, mk_rews, termless) + end; + +val (op del_congs) = foldl del_cong; + + +(* add_simprocs *) + +fun add_proc (mss as Mss {rules,congs,procs,bounds,prems,mk_rews,termless}, + (name, lhs as Cterm {sign_ref, t, ...}, proc, id)) = + (trace_term false ("Adding simplification procedure " ^ quote name ^ " for") + (Sign.deref sign_ref) t; + mk_mss (rules, congs, + Net.insert_term ((t, mk_simproc (name, proc, lhs, id)), procs, eq_simproc) + handle Net.INSERT => + (warning ("Ignoring duplicate simplification procedure \"" + ^ name ^ "\""); + procs), + bounds, prems, mk_rews, termless)); + +fun add_simproc (mss, (name, lhss, proc, id)) = + foldl add_proc (mss, map (fn lhs => (name, lhs, proc, id)) lhss); + +val add_simprocs = foldl add_simproc; + + +(* del_simprocs *) + +fun del_proc (mss as Mss {rules,congs,procs,bounds,prems,mk_rews,termless}, + (name, lhs as Cterm {t, ...}, proc, id)) = + mk_mss (rules, congs, + Net.delete_term ((t, mk_simproc (name, proc, lhs, id)), procs, eq_simproc) + handle Net.DELETE => + (warning ("Simplification procedure \"" ^ name ^ + "\" not in simpset"); procs), + bounds, prems, mk_rews, termless); + +fun del_simproc (mss, (name, lhss, proc, id)) = + foldl del_proc (mss, map (fn lhs => (name, lhs, proc, id)) lhss); + +val del_simprocs = foldl del_simproc; + + +(* prems *) + +fun add_prems (Mss {rules,congs,procs,bounds,prems,mk_rews,termless}, thms) = + mk_mss (rules, congs, procs, bounds, thms @ prems, mk_rews, termless); + +fun prems_of_mss (Mss {prems, ...}) = prems; + + +(* mk_rews *) + +fun set_mk_rews + (Mss {rules, congs, procs, bounds, prems, mk_rews, termless}, mk) = + mk_mss (rules, congs, procs, bounds, prems, + {mk=mk, mk_sym= #mk_sym mk_rews, mk_eq_True= #mk_eq_True mk_rews}, + termless); + +fun set_mk_sym + (Mss {rules, congs, procs, bounds, prems, mk_rews, termless}, mk_sym) = + mk_mss (rules, congs, procs, bounds, prems, + {mk= #mk mk_rews, mk_sym= mk_sym, mk_eq_True= #mk_eq_True mk_rews}, + termless); + +fun set_mk_eq_True + (Mss {rules, congs, procs, bounds, prems, mk_rews, termless}, mk_eq_True) = + mk_mss (rules, congs, procs, bounds, prems, + {mk= #mk mk_rews, mk_sym= #mk_sym mk_rews, mk_eq_True= mk_eq_True}, + termless); + +(* termless *) + +fun set_termless + (Mss {rules, congs, procs, bounds, prems, mk_rews, termless = _}, termless) = + mk_mss (rules, congs, procs, bounds, prems, mk_rews, termless); + + + +(** rewriting **) + +(* + Uses conversions, omitting proofs for efficiency. See: + L C Paulson, A higher-order implementation of rewriting, + Science of Computer Programming 3 (1983), pages 119-149. +*) + +type prover = meta_simpset -> thm -> thm option; +type termrec = (Sign.sg_ref * term list) * term; +type conv = meta_simpset -> termrec -> termrec; + +fun check_conv + (thm as Thm{shyps,hyps,prop,sign_ref,der,...}, prop0, ders) = + let fun err() = (trace_thm false "Proved wrong thm (Check subgoaler?)" thm; + trace_term false "Should have proved:" (Sign.deref sign_ref) prop0; + None) + val (lhs0,_) = Logic.dest_equals(Logic.strip_imp_concl prop0) + in case prop of + Const("==",_) $ lhs $ rhs => + if (lhs = lhs0) orelse + (lhs aconv Envir.norm_term (Envir.empty 0) lhs0) + then (trace_thm false "SUCCEEDED" thm; + Some(rhs, (shyps, hyps, der::ders))) + else err() + | _ => err() + end; + +fun ren_inst(insts,prop,pat,obj) = + let val ren = match_bvs(pat,obj,[]) + fun renAbs(Abs(x,T,b)) = + Abs(if_none(assoc_string(ren,x)) x, T, renAbs(b)) + | renAbs(f$t) = renAbs(f) $ renAbs(t) + | renAbs(t) = t + in subst_vars insts (if null(ren) then prop else renAbs(prop)) end; + +fun incr_insts i (in1:(indexname*typ)list,in2:(indexname*term)list) = + let fun incr ((a,n),x) = ((a,n+i),x) + in (map incr in1, map incr in2) end; + +fun add_insts_sorts ((iTs, is), Ss) = + add_typs_sorts (map snd iTs, add_terms_sorts (map snd is, Ss)); + + +(* mk_procrule *) + +fun mk_procrule thm = + let val (_,prems,lhs,elhs,rhs,_) = decomp_simp thm + in if rewrite_rule_extra_vars prems lhs rhs + then (prthm true "Extra vars on rhs:" thm; []) + else [mk_rrule2{thm=thm, lhs=lhs, elhs=elhs, perm=false}] + end; + + +(* conversion to apply the meta simpset to a term *) + +(* Since the rewriting strategy is bottom-up, we avoid re-normalizing already + normalized terms by carrying around the rhs of the rewrite rule just + applied. This is called the `skeleton'. It is decomposed in parallel + with the term. Once a Var is encountered, the corresponding term is + already in normal form. + skel0 is a dummy skeleton that is to enforce complete normalization. +*) +val skel0 = Bound 0; + +(* Use rhs as skeleton only if the lhs does not contain unnormalized bits. + The latter may happen iff there are weak congruence rules for constants + in the lhs. +*) +fun uncond_skel((_,weak),(lhs,rhs)) = + if null weak then rhs (* optimization *) + else if exists_Const (fn (c,_) => c mem weak) lhs then skel0 + else rhs; + +(* Behaves like unconditional rule if rhs does not contain vars not in the lhs. + Otherwise those vars may become instantiated with unnormalized terms + while the premises are solved. +*) +fun cond_skel(args as (congs,(lhs,rhs))) = + if term_varnames rhs subset term_varnames lhs then uncond_skel(args) + else skel0; + +(* + we try in order: + (1) beta reduction + (2) unconditional rewrite rules + (3) conditional rewrite rules + (4) simplification procedures + + IMPORTANT: rewrite rules must not introduce new Vars or TVars! + +*) + +fun rewritec (prover,sign_reft,maxt) + (mss as Mss{rules, procs, termless, prems, congs, ...}) + (t:term,etc as (shypst,hypst,ders)) = + let + val eta_t = Pattern.eta_contract t; + val signt = Sign.deref sign_reft; + val tsigt = Sign.tsig_of signt; + fun rew{thm as Thm{sign_ref,der,shyps,hyps,prop,maxidx,...}, + lhs, elhs, fo, perm} = + let + val _ = if Sign.subsig (Sign.deref sign_ref, signt) then () + else (prthm true "Ignoring rewrite rule from different theory:" thm; + raise Pattern.MATCH); + val rprop = if maxt = ~1 then prop + else Logic.incr_indexes([],maxt+1) prop; + val insts = if fo then Pattern.first_order_match tsigt (elhs,eta_t) + else Pattern.match tsigt (elhs,eta_t); + val insts = if maxt = ~1 then insts else incr_insts (maxt+1) insts + val prop' = ren_inst(insts,rprop,lhs,eta_t); + val hyps' = union_term(hyps,hypst); + val shyps' = add_insts_sorts (insts, union_sort(shyps,shypst)); + val unconditional = (Logic.count_prems(prop',0) = 0); + val maxidx' = if unconditional then maxt else maxidx+maxt+1 + val ct' = Cterm{sign_ref = sign_reft, (*used for deriv only*) + t = prop', T = propT, maxidx = maxidx'} + val der' = infer_derivs (RewriteC ct', [der]); + val thm' = Thm{sign_ref = sign_reft, der = der', shyps = shyps', + hyps = hyps', prop = prop', maxidx = maxidx'} + val (lhs',rhs') = Logic.dest_equals(Logic.strip_imp_concl prop') + in + if perm andalso not(termless(rhs',lhs')) then None + else + (trace_thm false "Applying instance of rewrite rule:" thm; + if unconditional + then + (trace_thm false "Rewriting:" thm'; + let val lr = Logic.dest_equals prop + val trec' = (rhs', (shyps', hyps', der'::ders)) + in Some(trec',uncond_skel(congs,lr)) end) + else + (trace_thm false "Trying to rewrite:" thm'; + case prover mss thm' of + None => (trace_thm false "FAILED" thm'; None) + | Some(thm2) => + (case check_conv(thm2,prop',ders) of + None => None | + Some trec => + let val concl = Logic.strip_imp_concl prop + val lr = Logic.dest_equals concl + in Some(trec,cond_skel(congs,lr)) end))) + end + + fun rews [] = None + | rews (rrule :: rrules) = + let val opt = rew rrule handle Pattern.MATCH => None + in case opt of None => rews rrules | some => some end; + + fun sort_rrules rrs = let + fun is_simple({thm as Thm{prop,...}, ...}:rrule) = case prop of + Const("==",_) $ _ $ _ => true + | _ => false + fun sort [] (re1,re2) = re1 @ re2 + | sort (rr::rrs) (re1,re2) = if is_simple rr + then sort rrs (rr::re1,re2) + else sort rrs (re1,rr::re2) + in sort rrs ([],[]) end + + fun proc_rews ([]:simproc list) = None + | proc_rews ({name, proc, lhs = Cterm {t = plhs, ...}, ...} :: ps) = + if Pattern.matches tsigt (plhs, t) then + (debug_term false ("Trying procedure " ^ quote name ^ " on:") signt eta_t; + case proc signt prems eta_t of + None => (debug false "FAILED"; proc_rews ps) + | Some raw_thm => + (trace_thm false ("Procedure " ^ quote name ^ " produced rewrite rule:") raw_thm; + (case rews (mk_procrule raw_thm) of + None => (trace false "IGNORED"; proc_rews ps) + | some => some))) + else proc_rews ps; + in case eta_t of + Abs (_, _, body) $ u => Some ((subst_bound (u, body), etc),skel0) + | _ => (case rews (sort_rrules (Net.match_term rules eta_t)) of + None => proc_rews (Net.match_term procs eta_t) + | some => some) + end; + + +(* conversion to apply a congruence rule to a term *) + +fun congc (prover,sign_reft,maxt) {thm=cong,lhs=lhs} (t,(shypst,hypst,ders)) = + let val signt = Sign.deref sign_reft; + val tsig = Sign.tsig_of signt; + val Thm{sign_ref,der,shyps,hyps,maxidx,prop,...} = cong + val _ = if Sign.subsig(Sign.deref sign_ref,signt) then () + else error("Congruence rule from different theory") + val rprop = if maxt = ~1 then prop + else Logic.incr_indexes([],maxt+1) prop; + val rlhs = if maxt = ~1 then lhs + else fst(Logic.dest_equals(Logic.strip_imp_concl rprop)) + val insts = Pattern.match tsig (rlhs,t) + (* Pattern.match can raise Pattern.MATCH; + is handled when congc is called *) + val prop' = ren_inst(insts,rprop,rlhs,t); + val shyps' = add_insts_sorts (insts, union_sort(shyps,shypst)) + val maxidx' = maxidx_of_term prop' + val ct' = Cterm{sign_ref = sign_reft, (*used for deriv only*) + t = prop', + T = propT, + maxidx = maxidx'} + val thm' = Thm{sign_ref = sign_reft, + der = infer_derivs (CongC ct', [der]), + shyps = shyps', + hyps = union_term(hyps,hypst), + prop = prop', + maxidx = maxidx'}; + val unit = trace_thm false "Applying congruence rule:" thm'; + fun err(msg,thm) = (prthm false msg thm; error("Failed congruence proof!")) + + in case prover thm' of + None => err("Could not prove",thm') + | Some(thm2) => (case check_conv(thm2,prop',ders) of + None => err("Should not have proved",thm2) | Some trec => trec) + end; + +fun bottomc ((simprem,useprem,mutsimp),prover,sign_ref,maxidx) = + let + fun botc fail skel mss trec = + if is_Var skel then if fail then None else Some(trec) + else + (case subc skel mss trec of + some as Some(trec1) => + (case rewritec (prover,sign_ref,maxidx) mss trec1 of + Some(trec2,skel2) => botc false skel2 mss trec2 + | None => some) + | None => + (case rewritec (prover,sign_ref,maxidx) mss trec of + Some(trec2,skel2) => botc false skel2 mss trec2 + | None => if fail then None else Some(trec))) + + and try_botc mss trec = + (case botc true skel0 mss trec of + Some(trec1) => trec1 | None => trec) + + and subc skel + (mss as Mss{rules,congs,procs,bounds,prems,mk_rews,termless}) + (trec as (t0:term,etc:sort list*term list * (bool * deriv) list)) = + (case t0 of + Abs(a,T,t) => + let val b = variant bounds a + val v = Free("." ^ b,T) + val mss' = mk_mss (rules, congs, procs, b :: bounds, prems, mk_rews, termless) + val skel' = case skel of Abs(_,_,sk) => sk | _ => skel0 + in case botc true skel' mss' (subst_bound(v,t),etc) of + Some(t',etc') => Some(Abs(a, T, abstract_over(v,t')), etc') + | None => None + end + | t$u => (case t of + Const("==>",_)$s => Some(impc(s,u,mss,etc)) + | Abs(_,_,body) => + let val trec = (subst_bound(u,body), etc) + in case subc skel0 mss trec of + None => Some(trec) + | trec => trec + end + | _ => + let fun appc() = + let val (tskel,uskel) = + case skel of tskel$uskel => (tskel,uskel) + | _ => (skel0,skel0) + in + (case botc true tskel mss (t,etc) of + Some(t1,etc1) => + (case botc true uskel mss (u,etc1) of + Some(u1,etc2) => Some(t1$u1, etc2) + | None => Some(t1$u, etc1)) + | None => + (case botc true uskel mss (u,etc) of + Some(u1,etc1) => Some(t$u1, etc1) + | None => None)) + end + val (h,ts) = strip_comb t + in case h of + Const(a,_) => + (case assoc_string(fst congs,a) of + None => appc() + | Some(cong) => +(* post processing: some partial applications h t1 ... tj, j <= length ts, + may be a redex. Example: map (%x.x) = (%xs.xs) wrt map_cong *) + (let val ctrec as (t,etc) = + congc (prover mss,sign_ref,maxidx) cong trec + in case t of + l$r => + let val dVar = Var(("",0),dummyT) + val skel = + list_comb(h,replicate (length ts) dVar) + in case botc true skel mss (l,etc) of + None => Some ctrec + | Some(l',etc') => Some(l'$r,etc') + end + | _ => error "congc result" + end + handle Pattern.MATCH => appc() ) ) + | _ => appc() + end) + | _ => None) + + and impc args = + if mutsimp + then let val (prem, conc, mss, etc) = args + in snd(mut_impc([], prem, conc, mss, etc)) end + else nonmut_impc args + + and mut_impc (prems, prem, conc, mss, etc) = + let val (prem1,etc1) = try_botc mss (prem,etc) + in mut_impc1(prems, prem1, conc, mss, etc1) end + + and mut_impc1(prems, prem1, conc, mss, etc1 as (_,hyps1,_)) = + let + fun uncond({thm,lhs,elhs,perm}) = + if no_prems thm then Some lhs else None + + val (lhss1,mss1) = + if maxidx_of_term prem1 <> ~1 + then (trace_term true "Cannot add premise as rewrite rule because it contains (type) unknowns:" + (Sign.deref sign_ref) prem1; + ([],mss)) + else let val thm = assume (Cterm{sign_ref=sign_ref, t=prem1, + T=propT, maxidx= ~1}) + val rrules1 = extract_safe_rrules(mss,thm) + val lhss1 = mapfilter uncond rrules1 + val mss1 = foldl insert_rrule (add_prems(mss,[thm]),rrules1) + in (lhss1, mss1) end + + fun disch1(conc2,(shyps2,hyps2,ders2)) = + let val hyps2' = if gen_mem (op aconv) (prem1, hyps1) + then hyps2 else hyps2\prem1 + in (Logic.mk_implies(prem1,conc2),(shyps2,hyps2',ders2)) end + + fun rebuild trec2 = + let val trec = disch1 trec2 + in case rewritec (prover,sign_ref,maxidx) mss trec of + None => (None,trec) + | Some((Const("==>",_)$prem$conc,etc),_) => + mut_impc(prems,prem,conc,mss,etc) + | Some(trec',_) => (None,trec') + end + + fun simpconc() = + case conc of + Const("==>",_)$s$t => + (case mut_impc(prems@[prem1],s,t,mss1,etc1) of + (Some(i,prem),trec2) => + let val trec2' = disch1 trec2 + in if i=0 then mut_impc1(prems,prem,fst trec2',mss,snd trec2') + else (Some(i-1,prem),trec2') + end + | (None,trec) => rebuild(trec)) + | _ => rebuild(try_botc mss1 (conc,etc1)) + + in let val sg = Sign.deref sign_ref + val tsig = #tsig(Sign.rep_sg sg) + fun reducible t = + exists (fn lhs => Pattern.matches_subterm tsig (lhs,t)) + lhss1; + in case dropwhile (not o reducible) prems of + [] => simpconc() + | red::rest => (trace_term false "Can now reduce premise:" sg + red; + (Some(length rest,prem1),(conc,etc1))) + end + end + + (* legacy code - only for backwards compatibility *) + and nonmut_impc(prem, conc, mss, etc as (_,hyps1,_)) = + let val (prem1,etc1) = if simprem then try_botc mss (prem,etc) + else (prem,etc) + val maxidx1 = maxidx_of_term prem1 + val mss1 = + if not useprem then mss else + if maxidx1 <> ~1 + then (trace_term true "Cannot add premise as rewrite rule because it contains (type) unknowns:" + (Sign.deref sign_ref) prem1; + mss) + else let val thm = assume (Cterm{sign_ref=sign_ref, t=prem1, + T=propT, maxidx= ~1}) + in add_safe_simp(add_prems(mss,[thm]), thm) end + val (conc2,(shyps2,hyps2,ders2)) = try_botc mss1 (conc,etc1) + val hyps2' = if prem1 mem hyps1 then hyps2 else hyps2\prem1 + in (Logic.mk_implies(prem1,conc2), (shyps2, hyps2', ders2)) end + + in try_botc end; + + +(*** Meta-rewriting: rewrites t to u and returns the theorem t==u ***) + +(* + Parameters: + mode = (simplify A, + use A in simplifying B, + use prems of B (if B is again a meta-impl.) to simplify A) + when simplifying A ==> B + mss: contains equality theorems of the form [|p1,...|] ==> t==u + prover: how to solve premises in conditional rewrites and congruences +*) + +(* FIXME: check that #bounds(mss) does not "occur" in ct alread *) + +fun rewrite_cterm mode mss prover ct = + let val Cterm {sign_ref, t, T, maxidx} = ct; + val (u,(shyps,hyps,ders)) = bottomc (mode,prover, sign_ref, maxidx) mss + (t, (add_term_sorts(t,[]), [], [])); + val prop = Logic.mk_equals(t,u) + in + Thm{sign_ref = sign_ref, + der = infer_derivs (Rewrite_cterm ct, ders), + maxidx = maxidx, + shyps = shyps, + hyps = hyps, + prop = prop} + end; + + + (*** Oracles ***) fun invoke_oracle thy raw_name =