X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Fsuperposition.ml;h=82fe83037b0a92ebe287dcd4114aa716b2d99c0c;hb=9a7efce50583b19214320afac57fb90ae78353ea;hp=046799a775149470bd7162252b023e582ffb9e99;hpb=8bb849acb32ab6180be4ea23dbb9fe35d7300ceb;p=helm.git diff --git a/helm/software/components/ng_paramodulation/superposition.ml b/helm/software/components/ng_paramodulation/superposition.ml index 046799a77..82fe83037 100644 --- a/helm/software/components/ng_paramodulation/superposition.ml +++ b/helm/software/components/ng_paramodulation/superposition.ml @@ -15,7 +15,7 @@ module Superposition (B : Terms.Blob) = struct module IDX = Index.Index(B) module Unif = FoUnif.Founif(B) - module Subst = FoSubst.Subst(B) + module Subst = FoSubst (*.Subst(B)*) module Order = Orderings.Orderings(B) module Utils = FoUtils.Utils(B) module Pp = Pp.Pp(B) @@ -23,7 +23,7 @@ module Superposition (B : Terms.Blob) = exception Success of B.t Terms.bag * int * B.t Terms.unit_clause let debug s = - ()(* prerr_endline s *) + () (* prerr_endline s *) ;; let rec list_first f = function @@ -35,7 +35,7 @@ module Superposition (B : Terms.Blob) = let rec aux pos ctx = function | Terms.Leaf _ as t -> f t pos ctx | Terms.Var _ -> None - | Terms.Node l as t-> + | Terms.Node l as t-> match f t pos ctx with | Some _ as x -> x | None -> @@ -72,6 +72,14 @@ module Superposition (B : Terms.Blob) = in aux pos ctx t ;; + + let vars_of_term t = + let rec aux acc = function + | Terms.Leaf _ -> acc + | Terms.Var i -> if (List.mem i acc) then acc else i::acc + | Terms.Node l -> List.fold_left aux acc l + in aux [] t + ;; let build_clause bag filter rule t subst vl id id2 pos dir = let proof = Terms.Step(rule,id,id2,dir,pos,subst) in @@ -85,7 +93,7 @@ module Superposition (B : Terms.Blob) = | t -> Terms.Predicate t in let bag, uc = - Utils.add_to_bag bag (0, literal, vl, proof) + Utils.add_to_bag bag (0, literal, vars_of_term t, proof) in Some (bag, uc) else @@ -112,7 +120,7 @@ module Superposition (B : Terms.Blob) = let newside = Subst.apply_subst subst newside in let o = Order.compare_terms newside side in (* Riazanov, pp. 45 (ii) *) - if o = Terms.Lt then + if o = Terms.Lt then Some (context newside, subst, varlist, id, pos, dir) else ((*prerr_endline ("Filtering: " ^ @@ -125,26 +133,48 @@ module Superposition (B : Terms.Blob) = (IDX.ClauseSet.elements cands) ;; - (* XXX: possible optimization, if the literal has a "side" already - * in normal form we should not traverse it again *) - let demodulate_once bag (id, literal, vl, pr) table = - debug ("Demodulating : " ^ (Pp.pp_unit_clause (id, literal, vl, pr))); - let t = - match literal with - | Terms.Predicate t -> t - | Terms.Equation (l,r,ty,_) -> Terms.Node [ Terms.Leaf B.eqP; ty; l; r ] - in - match first_position [] (fun x -> x) t (demod table vl) with - | None -> None - | Some (newt, subst, varlist, id2, pos, dir) -> - build_clause bag (fun _ -> true) Terms.Demodulation - newt subst varlist id id2 pos dir + let demodulate_once ~jump_to_right bag (id, literal, vl, pr) table = + (* debug ("Demodulating : " ^ (Pp.pp_unit_clause (id, literal, vl, pr)));*) + match literal with + | Terms.Predicate t -> assert false + | Terms.Equation (l,r,ty,_) -> + let left_position = if jump_to_right then None else + first_position [2] + (fun x -> Terms.Node [ Terms.Leaf B.eqP; ty; x; r ]) l + (demod table vl) + in + match left_position with + | Some (newt, subst, varlist, id2, pos, dir) -> + begin + match build_clause bag (fun _ -> true) Terms.Demodulation + newt subst varlist id id2 pos dir + with + | None -> assert false + | Some x -> Some (x,false) + end + | None -> + match first_position + [3] (fun x -> Terms.Node [ Terms.Leaf B.eqP; ty; l; x ]) r + (demod table vl) + with + | None -> None + | Some (newt, subst, varlist, id2, pos, dir) -> + match build_clause bag (fun _ -> true) + Terms.Demodulation newt subst varlist id id2 pos dir + with + | None -> assert false + | Some x -> Some (x,true) ;; - let rec demodulate bag clause table = - match demodulate_once bag clause table with + let rec demodulate ~jump_to_right bag clause table = + match demodulate_once ~jump_to_right bag clause table with | None -> bag, clause - | Some (bag, clause) -> demodulate bag clause table + | Some ((bag, clause),r) -> demodulate ~jump_to_right:r + bag clause table + ;; + + let demodulate bag clause table = demodulate ~jump_to_right:false + bag clause table ;; (* move away *) @@ -154,7 +184,26 @@ module Superposition (B : Terms.Blob) = | _ -> false ;; - let is_subsumed ~unify (id, lit, vl, _) table = + let build_new_clause bag maxvar filter rule t subst vl id id2 pos dir = + let maxvar, vl, relocsubst = Utils.relocate maxvar vl in + let subst = Subst.concat relocsubst subst in + match build_clause bag filter rule t subst vl id id2 pos dir with + | Some (bag, c) -> Some ((bag, maxvar), c) + | None -> None + ;; + + + let fold_build_new_clause bag maxvar id rule filter res = + let (bag, maxvar), res = + HExtlib.filter_map_acc + (fun (bag, maxvar) (t,subst,vl,id2,pos,dir) -> + build_new_clause bag maxvar filter rule t subst vl id id2 pos dir) + (bag, maxvar) res + in + bag, maxvar, res + ;; + + let is_subsumed ~unify bag maxvar (id, lit, vl, _) table = match lit with | Terms.Predicate _ -> assert false | Terms.Equation (l,r,ty,_) -> @@ -163,48 +212,79 @@ module Superposition (B : Terms.Blob) = let lcands = retrieve table l in let rcands = retrieve table r in let f b c = - let dir, l, r, vl = + let id, dir, l, r, vl = match c with - | (d, (_,Terms.Equation (l,r,ty,_),vl,_))-> d, l, r, vl + | (d, (id,Terms.Equation (l,r,ty,_),vl,_))-> id, d, l, r, vl |_ -> assert false in - let l, r = if (dir = Terms.Left2Right) = b then l,r else r,l in - Terms.Node [ Terms.Leaf B.eqP; ty; l; r ], vl + let reverse = (dir = Terms.Left2Right) = b in + let l, r, proof_rewrite_dir = if reverse then l,r,Terms.Left2Right + else r,l, Terms.Right2Left in + (id,proof_rewrite_dir,Terms.Node [ Terms.Leaf B.eqP; ty; l; r ], vl) in let cands1 = List.map (f true) (IDX.ClauseSet.elements lcands) in let cands2 = List.map (f false) (IDX.ClauseSet.elements rcands) in let t = Terms.Node [ Terms.Leaf B.eqP; ty; l; r ] in let locked_vars = if unify then [] else vl in - List.exists - (fun (c, vl1) -> - try ignore(Unif.unification (vl@vl1) locked_vars c t); true - with FoUnif.UnificationFailure _ -> false) - (cands1 @ cands2) + let rec aux = function + | [] -> None + | (id2,dir,c,vl1)::tl -> + try + let subst,vl1 = Unif.unification (vl@vl1) locked_vars c t in + let id_t = Terms.Node [ Terms.Leaf B.eqP; ty; r; r ] in + build_new_clause bag maxvar (fun _ -> true) + Terms.Superposition id_t subst [] id id2 [2] dir + with FoUnif.UnificationFailure _ -> aux tl + in + aux (cands1 @ cands2) ;; (* demodulate and check for subsumption *) - let simplify table bag clause = + let simplify table maxvar bag clause = let bag, clause = demodulate bag clause table in if is_identity_clause clause then None else - if is_subsumed ~unify:false clause table then None - else Some (bag, clause) + match is_subsumed ~unify:false bag maxvar clause table with + | None -> Some (bag, clause) + | Some _ -> None + ;; + + let one_pass_simplification new_clause (alist,atable) bag maxvar = + match simplify atable maxvar bag new_clause with + | None -> None (* new_clause has been discarded *) + | Some (bag, clause) -> + let ctable = IDX.index_unit_clause IDX.DT.empty clause in + let bag, alist, atable = + List.fold_left + (fun (bag, alist, atable as acc) c -> + match simplify ctable maxvar bag c with + |None -> acc (* an active clause as been discarded *) + |Some (bag, c1) -> + bag, c :: alist, IDX.index_unit_clause atable c) + (bag,[],IDX.DT.empty) alist + in + Some (clause, bag, (alist,atable)) ;; - let simplification_step ~new_cl cl (alist,atable) bag new_clause = + let simplification_step ~new_cl cl (alist,atable) bag maxvar new_clause = let atable1 = if new_cl then atable else IDX.index_unit_clause atable cl in - match simplify atable1 bag new_clause with - | None -> (Some cl, None) + (* Simplification of new_clause with : * + * - actives and cl if new_clause is not cl * + * - only actives otherwise *) + match simplify atable1 maxvar bag new_clause with + | None -> (Some cl, None) (* new_clause has been discarded *) | Some (bag, clause) -> + (* Simplification of each active clause with clause * + * which is the simplified form of new_clause *) let ctable = IDX.index_unit_clause IDX.DT.empty clause in let bag, newa, alist, atable = List.fold_left (fun (bag, newa, alist, atable as acc) c -> - match simplify ctable bag c with - |None -> acc + match simplify ctable maxvar bag c with + |None -> acc (* an active clause as been discarded *) |Some (bag, c1) -> if (c1 == c) then bag, newa, c :: alist, @@ -216,17 +296,19 @@ module Superposition (B : Terms.Blob) = if new_cl then (Some cl, Some (clause, (alist,atable), newa, bag)) else - match simplify ctable bag cl with + (* if new_clause is not cl, we simplify cl with clause *) + match simplify ctable maxvar bag cl with | None -> + (* cl has been discarded *) (None, Some (clause, (alist,atable), newa, bag)) | Some (bag,cl1) -> (Some cl1, Some (clause, (alist,atable), newa, bag)) ;; - let keep_simplified cl (alist,atable) bag = + let keep_simplified cl (alist,atable) bag maxvar = let rec keep_simplified_aux ~new_cl cl (alist,atable) bag newc = if new_cl then - match simplification_step ~new_cl cl (alist,atable) bag cl with + match simplification_step ~new_cl cl (alist,atable) bag maxvar cl with | (None, _) -> assert false | (Some _, None) -> None | (Some _, Some (clause, (alist,atable), newa, bag)) -> @@ -237,7 +319,7 @@ module Superposition (B : Terms.Blob) = | [] -> Some (cl, bag, (alist,atable)) | hd::tl -> match simplification_step ~new_cl cl - (alist,atable) bag hd with + (alist,atable) bag maxvar hd with | (None,None) -> assert false | (Some _,None) -> keep_simplified_aux ~new_cl cl (alist,atable) bag tl @@ -255,9 +337,13 @@ module Superposition (B : Terms.Blob) = (* this is like simplify but raises Success *) let simplify_goal maxvar table bag clause = let bag, clause = demodulate bag clause table in - if (is_identity_clause clause) || (is_subsumed ~unify:true clause table) + if (is_identity_clause clause) then raise (Success (bag, maxvar, clause)) - else bag, clause + else match is_subsumed ~unify:true bag maxvar clause table with + | None -> bag, clause + | Some ((bag,maxvar),c) -> + debug "Goal subsumed"; + raise (Success (bag,maxvar,c)) ;; (* =================== inference ===================== *) @@ -293,25 +379,6 @@ module Superposition (B : Terms.Blob) = (IDX.ClauseSet.elements cands) ;; - let build_new_clause bag maxvar filter rule t subst vl id id2 pos dir = - let maxvar, vl, relocsubst = Utils.relocate maxvar vl in - let subst = Subst.concat relocsubst subst in - match build_clause bag filter rule t subst vl id id2 pos dir with - | Some (bag, c) -> Some ((bag, maxvar), c) - | None -> None - ;; - - - let fold_build_new_clause bag maxvar id rule filter res = - let (bag, maxvar), res = - HExtlib.filter_map_acc - (fun (bag, maxvar) (t,subst,vl,id2,pos,dir) -> - build_new_clause bag maxvar filter rule t subst vl id id2 pos dir) - (bag, maxvar) res - in - bag, maxvar, res - ;; - (* Superposes selected equation with equalities in table *) let superposition_with_table bag maxvar (id,selected,vl,_) table = match selected with @@ -321,7 +388,7 @@ module Superposition (B : Terms.Blob) = (fun _ -> true) (all_positions [3] (fun x -> Terms.Node [ Terms.Leaf B.eqP; ty; l; x ]) - r (superposition table vl)) + r (superposition table vl)) | Terms.Equation (l,r,ty,Terms.Gt) -> fold_build_new_clause bag maxvar id Terms.Superposition (fun _ -> true) @@ -384,8 +451,10 @@ module Superposition (B : Terms.Blob) = in debug "Another superposition"; let new_clauses = new_clauses @ additional_new_clauses in + debug (Printf.sprintf "Demodulating %d clauses" + (List.length new_clauses)); let bag, new_clauses = - HExtlib.filter_map_acc (simplify atable) bag new_clauses + HExtlib.filter_map_acc (simplify atable maxvar) bag new_clauses in debug "Demodulated new clauses"; bag, maxvar, (alist, atable), new_clauses @@ -393,21 +462,20 @@ module Superposition (B : Terms.Blob) = let infer_left bag maxvar goal (_alist, atable) = (* We superpose the goal with active clauses *) - let bag, maxvar, new_goals = + let bag, maxvar, new_goals = superposition_with_table bag maxvar goal atable in - (* We demodulate the goal with active clauses *) + debug "Superposed goal with active clauses"; + (* We simplify the new goals with active clauses *) let bag, new_goals = List.fold_left (fun (bag, acc) g -> - let bag, g = demodulate bag g atable in - bag, g :: acc) + let bag, g = simplify_goal maxvar atable bag g in + bag,g::acc) (bag, []) new_goals in + debug "Simplified new goals with active clauses"; bag, maxvar, List.rev new_goals ;; end - - -