X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Fsuperposition.ml;h=61d6c0589f3ab9952e670ead382f71633ea00ef8;hb=1c9b8f3ba2c86446d44160ae494bc85624bc5eaf;hp=aef672c144f5b2ba307626217ce5d122260a8812;hpb=8863adcc7dc67d3f4f6ba96c2424698cd6b21446;p=helm.git diff --git a/helm/software/components/ng_paramodulation/superposition.ml b/helm/software/components/ng_paramodulation/superposition.ml index aef672c14..61d6c0589 100644 --- a/helm/software/components/ng_paramodulation/superposition.ml +++ b/helm/software/components/ng_paramodulation/superposition.ml @@ -120,7 +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: " ^ @@ -133,20 +133,25 @@ 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 = + 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,_) -> - match first_position [2] - (fun x -> Terms.Node [ Terms.Leaf B.eqP; ty; x; r ]) l - (demod table vl) - with + 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) -> - build_clause bag (fun _ -> true) Terms.Demodulation - newt subst varlist id 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 @@ -154,20 +159,31 @@ module Superposition (B : Terms.Blob) = with | None -> None | Some (newt, subst, varlist, id2, pos, dir) -> - build_clause bag (fun _ -> true) Terms.Demodulation - newt subst varlist id 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 *) - let is_identity_clause = function + let is_identity_clause ~unify = function | _, Terms.Equation (_,_,_,Terms.Eq), _, _ -> true - | _, Terms.Predicate _, _, _ -> assert false + | _, Terms.Equation (l,r,_,_), vl, proof when unify -> + (try ignore(Unif.unification vl [] l r); true + with FoUnif.UnificationFailure _ -> false) + | _, Terms.Predicate _, _, _ -> assert false | _ -> false ;; @@ -190,46 +206,68 @@ module Superposition (B : Terms.Blob) = bag, maxvar, res ;; + + let rewrite_eq ~unify l r ty vl table = + let retrieve = if unify then IDX.DT.retrieve_unifiables + else IDX.DT.retrieve_generalizations in + let lcands = retrieve table l in + let rcands = retrieve table r in + let f b c = + let id, dir, l, r, vl = + match c with + | (d, (id,Terms.Equation (l,r,ty,_),vl,_))-> id, d, l, r, vl + |_ -> assert false + in + 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 + let rec aux = function + | [] -> None + | (id2,dir,c,vl1)::tl -> + try + let subst,vl1 = Unif.unification (vl@vl1) locked_vars c t in + Some (id2, dir, subst) + with FoUnif.UnificationFailure _ -> aux tl + in + aux (cands1 @ cands2) + ;; + let is_subsumed ~unify bag maxvar (id, lit, vl, _) table = match lit with | Terms.Predicate _ -> assert false | Terms.Equation (l,r,ty,_) -> - let retrieve = if unify then IDX.DT.retrieve_unifiables - else IDX.DT.retrieve_generalizations in - let lcands = retrieve table l in - let rcands = retrieve table r in - let f b c = - let id, dir, l, r, vl = - match c with - | (d, (id,Terms.Equation (l,r,ty,_),vl,_))-> id, d, l, r, vl - |_ -> assert false - in - 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 - 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) + match rewrite_eq ~unify l r ty vl table with + | None -> None + | Some (id2, dir, subst) -> + 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 ;; +(* + let rec deeply_subsumed ~unify bag maxvar (id, lit, vl, _) table = + match lit with + | Terms.Predicate _ -> assert false + | Terms.Equation (l,r,ty,_) -> + (match is_subsumed ~unify bag maxvar (id, lit, vl, _) table with + | Some((bag,maxvar),c) -> Some((bag,maxvar),c) + | None -> + match l,r with -> + Var i, _ -> + ;; +*) + + (* demodulate and check for subsumption *) let simplify table maxvar bag clause = let bag, clause = demodulate bag clause table in - if is_identity_clause clause then None + if is_identity_clause ~unify:false clause then None else match is_subsumed ~unify:false bag maxvar clause table with | None -> Some (bag, clause) @@ -319,15 +357,28 @@ module Superposition (B : Terms.Blob) = bag (newa@tl) in keep_simplified_aux ~new_cl:true cl (alist,atable) bag [] - ;; - + ;; + + let are_alpha_eq cl1 cl2 = + let get_term (_,lit,_,_) = + match lit with + | Terms.Predicate _ -> assert false + | Terms.Equation (l,r,ty,_) -> + Terms.Node [Terms.Leaf B.eqP; ty; l ; r] + in + try ignore(Unif.alpha_eq (get_term cl1) (get_term cl2)) ; true + with FoUnif.UnificationFailure _ -> false +;; + (* this is like simplify but raises Success *) - let simplify_goal maxvar table bag clause = + let simplify_goal maxvar table bag g_actives clause = let bag, clause = demodulate bag clause table in - if (is_identity_clause clause) + if (is_identity_clause ~unify:true clause) then raise (Success (bag, maxvar, clause)) else match is_subsumed ~unify:true bag maxvar clause table with - | None -> bag, clause + | None -> + if List.exists (are_alpha_eq clause) g_actives then None + else Some (bag, clause) | Some ((bag,maxvar),c) -> debug "Goal subsumed"; raise (Success (bag,maxvar,c)) @@ -438,6 +489,8 @@ 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 maxvar) bag new_clauses in @@ -451,15 +504,16 @@ module Superposition (B : Terms.Blob) = superposition_with_table bag maxvar goal atable in debug "Superposed goal with active clauses"; - (* We demodulate the new goals 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) + match simplify_goal maxvar atable bag [] g with + | None -> assert false + | Some (bag,g) -> bag,g::acc) (bag, []) new_goals in - debug "Demodulated goal with active clauses"; + debug "Simplified new goals with active clauses"; bag, maxvar, List.rev new_goals ;;