X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Fsuperposition.ml;h=d058be2533fd83faf8e99a31fd4b0e99d0a58331;hb=2701c980f48541dd5e8317b5a5661b439ced8b29;hp=0fc1f750a6cc16d8fc99adfc75215157e06e9b13;hpb=a200ab05cafa2e2b1075d04235042ee8e99f046e;p=helm.git diff --git a/helm/software/components/ng_paramodulation/superposition.ml b/helm/software/components/ng_paramodulation/superposition.ml index 0fc1f750a..d058be253 100644 --- a/helm/software/components/ng_paramodulation/superposition.ml +++ b/helm/software/components/ng_paramodulation/superposition.ml @@ -22,9 +22,8 @@ module Superposition (B : Terms.Blob) = exception Success of B.t Terms.bag * int * B.t Terms.unit_clause - let debug s = - () (* prerr_endline s *) - ;; +(* let debug s = prerr_endline s;;*) + let debug _ = ();; let rec list_first f = function | [] -> None @@ -120,7 +119,7 @@ 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 +132,25 @@ 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 @@ -154,21 +158,32 @@ 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 - | _ -> false + | _, Terms.Equation (l,r,_,_), vl, proof when unify -> + (try ignore(Unif.unification vl [] l r); true + with FoUnif.UnificationFailure _ -> false) + | _, Terms.Equation (_,_,_,_), _, _ -> false + | _, Terms.Predicate _, _, _ -> assert false ;; let build_new_clause bag maxvar filter rule t subst vl id id2 pos dir = @@ -179,7 +194,6 @@ module Superposition (B : Terms.Blob) = | None -> None ;; - let fold_build_new_clause bag maxvar id rule filter res = let (bag, maxvar), res = HExtlib.filter_map_acc @@ -190,67 +204,151 @@ 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 ;; + (* id refers to a clause proving contextl l = contextr r *) + + let rec deep_eq ~unify l r ty pos contextl contextr table acc = + match acc with + | None -> None + | Some(bag,maxvar,[],subst) -> assert false + | Some(bag,maxvar,(id,_,vl,_)::clauses,subst) -> + let l = Subst.apply_subst subst l in + let r = Subst.apply_subst subst r in + try + let subst1,vl1 = Unif.unification vl [] l r in + Some(bag,maxvar,clauses,Subst.concat subst1 subst) + with FoUnif.UnificationFailure _ -> + match rewrite_eq ~unify l r ty vl table with + | Some (id2, dir, subst1) -> + let id_t = + Terms.Node[Terms.Leaf B.eqP;ty;contextl r;contextr r] in + (match + build_new_clause bag maxvar (fun _ -> true) + Terms.Superposition id_t subst1 [] id id2 (2::pos) dir + with + | Some ((bag, maxvar), c) -> + Some(bag,maxvar,c::clauses,Subst.concat subst1 subst) + | None -> assert false) + | None -> + match l,r with + | Terms.Node (a::la), Terms.Node (b::lb) when + a = b && List.length la = List.length lb -> + let acc,_,_,_ = + List.fold_left2 + (fun (acc,pre,postl,postr) a b -> + let newcl = + fun x -> contextl(Terms.Node (pre@(x::postl))) in + let newcr = + fun x -> contextr(Terms.Node (pre@(x::postr))) in + let newpos = List.length pre::pos in + let footail l = + if l = [] then [] else List.tl l in + (deep_eq ~unify a b ty + newpos newcl newcr table acc,pre@[b], + footail postl, footail postr)) + (acc,[a],List.tl la,List.tl lb) la lb + in acc + | Terms.Var _, _ + | _, Terms.Var _ -> assert false + | _,_ -> None + ;; + + let rec orphan_murder bag acc i = + match Terms.M.find i bag with + | (_,_,_,Terms.Exact _),discarded -> (discarded,acc) + | (_,_,_,Terms.Step (_,i1,i2,_,_,_)),true -> (true,acc) + | (_,_,_,Terms.Step (_,i1,i2,_,_,_)),false -> + if (List.mem i acc) then (false,acc) + else match orphan_murder bag acc i1 with + | (true,acc) -> (true,acc) + | (false,acc) -> + let (res,acc) = orphan_murder bag acc i2 in + if res then res,acc else res,i::acc +;; + + let orphan_murder bag cl = + let (id,_,_,_) = cl in + let (res,_) = orphan_murder bag [] id in + if res then debug "Orphan murdered"; res +;; (* 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 bag,None + (* else if orphan_murder bag clause then bag,None *) + else let bag, clause = demodulate bag clause table in + if is_identity_clause ~unify:false clause then bag,None else match is_subsumed ~unify:false bag maxvar clause table with - | None -> Some (bag, clause) - | Some _ -> None + | None -> bag, Some clause + | Some _ -> bag, None ;; + let simplify table maxvar bag clause = + match simplify table maxvar bag clause with + | bag, None -> let (id,_,_,_) = clause in + Terms.M.add id (clause,true) bag, None + | bag, Some clause -> bag, Some clause +;; + 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) -> + | bag,None -> bag,None (* new_clause has been discarded *) + | bag,(Some 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 -> + (fun (bag, alist, atable) c -> match simplify ctable maxvar bag c with - |None -> acc (* an active clause as been discarded *) - |Some (bag, c1) -> + |bag,None -> (bag,alist,atable) + (* an active clause as been discarded *) + |bag,Some c1 -> bag, c :: alist, IDX.index_unit_clause atable c) (bag,[],IDX.DT.empty) alist in - Some (clause, bag, (alist,atable)) + bag, Some (clause, (alist,atable)) ;; let simplification_step ~new_cl cl (alist,atable) bag maxvar new_clause = @@ -262,17 +360,18 @@ module Superposition (B : Terms.Blob) = * - 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) -> + | bag,None -> bag,(Some cl, None) (* new_clause has been discarded *) + | bag,Some 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 -> + (fun (bag, newa, alist, atable) c -> match simplify ctable maxvar bag c with - |None -> acc (* an active clause as been discarded *) - |Some (bag, c1) -> + |bag,None -> (bag, newa, alist, atable) + (* an active clause as been discarded *) + |bag,Some c1 -> if (c1 == c) then bag, newa, c :: alist, IDX.index_unit_clause atable c @@ -281,37 +380,37 @@ module Superposition (B : Terms.Blob) = (bag,[],[],IDX.DT.empty) alist in if new_cl then - (Some cl, Some (clause, (alist,atable), newa, bag)) + bag, (Some cl, Some (clause, (alist,atable), newa)) else (* if new_clause is not cl, we simplify cl with clause *) match simplify ctable maxvar bag cl with - | None -> + | bag,None -> (* cl has been discarded *) - (None, Some (clause, (alist,atable), newa, bag)) - | Some (bag,cl1) -> - (Some cl1, Some (clause, (alist,atable), newa, bag)) + bag,(None, Some (clause, (alist,atable), newa)) + | bag,Some cl1 -> + bag,(Some cl1, Some (clause, (alist,atable), newa)) ;; 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 maxvar cl with - | (None, _) -> assert false - | (Some _, None) -> None - | (Some _, Some (clause, (alist,atable), newa, bag)) -> + | _,(None, _) -> assert false + | bag,(Some _, None) -> bag,None + | bag,(Some _, Some (clause, (alist,atable), newa)) -> keep_simplified_aux ~new_cl:(cl!=clause) clause (alist,atable) bag (newa@newc) else match newc with - | [] -> Some (cl, bag, (alist,atable)) + | [] -> bag, Some (cl, (alist,atable)) | hd::tl -> match simplification_step ~new_cl cl (alist,atable) bag maxvar hd with - | (None,None) -> assert false - | (Some _,None) -> + | _,(None,None) -> assert false + | bag,(Some _,None) -> keep_simplified_aux ~new_cl cl (alist,atable) bag tl - | (None, Some _) -> None - | (Some cl1, Some (clause, (alist,atable), newa, bag)) -> + | bag,(None, Some _) -> bag,None + | bag,(Some cl1, Some (clause, (alist,atable), newa)) -> let alist,atable = (clause::alist, IDX.index_unit_clause atable clause) in @@ -319,18 +418,48 @@ 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 + let (id,lit,vl,_) = clause in + let l,r,ty = + match lit with + | Terms.Equation(l,r,ty,_) -> l,r,ty + | _ -> assert false + in + match deep_eq ~unify:true l r ty [] (fun x -> x) (fun x -> x) + table (Some(bag,maxvar,[clause],Subst.id_subst)) with + | None -> + if List.exists (are_alpha_eq clause) g_actives then None + else Some (bag, clause) + | Some (bag,maxvar,cl,subst) -> + debug "Goal subsumed"; + raise (Success (bag,maxvar,List.hd cl)) +*) 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)) + raise (Success (bag,maxvar,c)) ;; (* =================== inference ===================== *) @@ -438,8 +567,10 @@ 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 maxvar) bag new_clauses + HExtlib.filter_map_monad (simplify atable maxvar) bag new_clauses in debug "Demodulated new clauses"; bag, maxvar, (alist, atable), new_clauses @@ -450,16 +581,17 @@ module Superposition (B : Terms.Blob) = let bag, maxvar, new_goals = superposition_with_table bag maxvar goal atable in - prerr_endline "Superposed goal with active clauses"; - (* 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) + match simplify_goal maxvar atable bag [] g with + | None -> assert false + | Some (bag,g) -> bag,g::acc) (bag, []) new_goals in - prerr_endline "Demodulated goal with active clauses"; + debug "Simplified new goals with active clauses"; bag, maxvar, List.rev new_goals ;;