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)
exception Success of B.t Terms.bag * int * B.t Terms.unit_clause
+ let debug s =
+ () (* prerr_endline s *)
+ ;;
+
let rec list_first f = function
| [] -> None
| x::tl -> match f x with Some _ as x -> x | _ -> list_first f tl
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
| 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
if o = Terms.Incomparable then
let side = Subst.apply_subst subst side in
let newside = Subst.apply_subst subst newside in
- let o = Order.compare_terms side newside in
+ let o = Order.compare_terms newside side in
(* Riazanov, pp. 45 (ii) *)
if o = Terms.Lt then
Some (context newside, subst, varlist, id, pos, dir)
(* 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, _) table =
+ 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
| _ -> false
;;
- let is_subsumed (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,_) ->
- let lcands = IDX.DT.retrieve_generalizations table l in
- let rcands = IDX.DT.retrieve_generalizations table l in
+ 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 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
- List.exists
- (fun (c, vl1) ->
- try ignore(Unif.unification (vl@vl1) vl c t); true
- with FoUnif.UnificationFailure _ -> false)
- (cands1 @ cands2)
+ 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)
;;
(* demodulate and check for subsumption *)
- let forward_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 clause table then None
- else Some (bag, clause)
+ match is_subsumed ~unify:false bag maxvar clause table with
+ | None -> Some (bag, clause)
+ | Some _ -> None
;;
- (* this is like forward_simplify but raises Success *)
- let backward_simplify maxvar table bag 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) ->
+ 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 maxvar new_clause =
+ let atable1 =
+ if new_cl then atable else
+ IDX.index_unit_clause atable cl
+ in
+ (* 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 maxvar bag c with
+ |None -> acc (* an active clause as been discarded *)
+ |Some (bag, c1) ->
+ if (c1 == c) then
+ bag, newa, c :: alist,
+ IDX.index_unit_clause atable c
+ else
+ bag, c1 :: newa, alist, atable)
+ (bag,[],[],IDX.DT.empty) alist
+ in
+ if new_cl then
+ (Some cl, Some (clause, (alist,atable), newa, bag))
+ else
+ (* 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 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)) ->
+ keep_simplified_aux ~new_cl:(cl!=clause) clause (alist,atable)
+ bag (newa@newc)
+ else
+ match newc with
+ | [] -> Some (cl, bag, (alist,atable))
+ | hd::tl ->
+ match simplification_step ~new_cl cl
+ (alist,atable) bag maxvar hd with
+ | (None,None) -> assert false
+ | (Some _,None) ->
+ keep_simplified_aux ~new_cl cl (alist,atable) bag tl
+ | (None, Some _) -> None
+ | (Some cl1, Some (clause, (alist,atable), newa, bag)) ->
+ let alist,atable =
+ (clause::alist, IDX.index_unit_clause atable clause)
+ in
+ keep_simplified_aux ~new_cl:(cl!=cl1) cl1 (alist,atable)
+ bag (newa@tl)
+ in
+ keep_simplified_aux ~new_cl:true cl (alist,atable) bag []
+ ;;
+
+ (* 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 then raise (Success (bag, maxvar, clause))
- else bag, clause
+ if (is_identity_clause clause)
+ then raise (Success (bag, maxvar, 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 ===================== *)
(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
| Terms.Predicate _ -> assert false
(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)
(* the current equation is normal w.r.t. demodulation with atable
* (and is not the identity) *)
let infer_right bag maxvar current (alist,atable) =
+ (* We demodulate actives clause with current until all *
+ * active clauses are reduced w.r.t each other *)
+ (* let bag, (alist,atable) = keep_simplified (alist,atable) bag [current] in *)
let ctable = IDX.index_unit_clause IDX.DT.empty current in
- let bag, (alist, atable) =
+ (* let bag, (alist, atable) =
let bag, alist =
- HExtlib.filter_map_acc (forward_simplify ctable) bag alist
+ HExtlib.filter_map_acc (simplify ctable) bag alist
in
bag, (alist, List.fold_left IDX.index_unit_clause IDX.DT.empty alist)
- in
+ in*)
+ debug "Simplified active clauses with fact";
+ (* We superpose active clauses with current *)
let bag, maxvar, new_clauses =
List.fold_left
(fun (bag, maxvar, acc) active ->
bag, maxvar, newc @ acc)
(bag, maxvar, []) alist
in
+ debug "First superpositions";
+ (* We add current to active clauses so that it can be *
+ * superposed with itself *)
let alist, atable =
current :: alist, IDX.index_unit_clause atable current
in
+ debug "Indexed";
let fresh_current, maxvar = Utils.fresh_unit_clause maxvar current in
+ (* We need to put fresh_current into the bag so that all *
+ * variables clauses refer to are known. *)
+ let bag, fresh_current = Utils.add_to_bag bag fresh_current in
+ (* We superpose current with active clauses *)
let bag, maxvar, additional_new_clauses =
superposition_with_table bag maxvar fresh_current atable
in
+ debug "Another superposition";
let new_clauses = new_clauses @ additional_new_clauses in
let bag, new_clauses =
- HExtlib.filter_map_acc (forward_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
;;
let infer_left bag maxvar goal (_alist, atable) =
+ (* We superpose the goal with active clauses *)
let bag, maxvar, new_goals =
superposition_with_table bag maxvar goal atable
in
+ (* We demodulate the goal with active clauses *)
let bag, new_goals =
List.fold_left
(fun (bag, acc) g ->
;;
end
-
-
-
projects / helm.git / blobdiff