- 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