X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Forderings.ml;h=51b48a4c32951f4fc7c9cc9ea2a9ca18a0df5ab9;hb=2e11e475e62e4f3d6872554fb504d77bf2327b7d;hp=dde09e81f6a0087b46237aaad8421d5e96b52ea7;hpb=6c4056ea40b96039f24eeda9a1e1900c95bad7c8;p=helm.git

diff --git a/helm/software/components/ng_paramodulation/orderings.ml b/helm/software/components/ng_paramodulation/orderings.ml
index dde09e81f..51b48a4c3 100644
--- a/helm/software/components/ng_paramodulation/orderings.ml
+++ b/helm/software/components/ng_paramodulation/orderings.ml
@@ -11,6 +11,8 @@
 
 (* $Id$ *)
 
+type aux_comparison = XEQ | XLE | XGE | XLT | XGT | XINCOMPARABLE
+
 module Orderings (B : Terms.Blob) = struct
 
   type weight = int * (int * int) list;;
@@ -42,203 +44,172 @@ module Orderings (B : Terms.Blob) = struct
     in
     let compare w1 w2 = 
       match w1, w2 with
-      | (m1, _), (m2, _) -> m2 - m1 
+      | (m1, _), (m2, _) -> m1 - m2
     in 
-    (w, List.sort compare l) (* from the biggest meta to the smallest (0) *)
-  ;;
-  
-  let compute_clause_weight = assert false (*
-    let factor = 2 in
-    match o with
-      | Terms.Lt -> 
-  	let w, m = (weight_of_term 
-  	       ~consider_metas:true ~count_metas_occurrences:false right) in
-  	  w + (factor * (List.length m)) ;
-      | Terms.Le -> assert false
-      | Terms.Gt -> 
-  	let w, m = (weight_of_term 
-  	       ~consider_metas:true ~count_metas_occurrences:false left) in
-  	  w + (factor * (List.length m)) ;
-    | Terms.Ge -> assert false
-    | Terms.Eq 
-    | Terms.Incomparable -> 
-        let w1, m1 = (weight_of_term 
-  	       ~consider_metas:true ~count_metas_occurrences:false right) in
-        let w2, m2 = (weight_of_term 
-  	       ~consider_metas:true ~count_metas_occurrences:false left) in
-        w1 + w2 + (factor * (List.length m1)) + (factor * (List.length m2))
-  *)
-  ;;
-  
-  (* returns a "normalized" version of the polynomial weight wl (with type
-   * weight list), i.e. a list sorted ascending by meta number,
-   * from 0 to maxmeta. wl must be sorted descending by meta number. Example:
-   * normalize_weight 5 (3, [(3, 2); (1, 1)]) ->
-   *      (3, [(1, 1); (2, 0); (3, 2); (4, 0); (5, 0)]) *)
-  let normalize_weight maxmeta (cw, wl) =
-    let rec aux = function
-      | 0 -> []
-      | m -> (m, 0)::(aux (m-1))
-    in
-    let tmpl = aux maxmeta in
-    let wl =
-      List.sort
-        (fun (m, _) (n, _) -> Pervasives.compare m n)
-        (List.fold_left
-           (fun res (m, w) -> (m, w)::(List.remove_assoc m res)) tmpl wl)
-    in
-    (cw, wl)
+    (w, List.sort compare l) (* from the smallest meta to the bigest *)
   ;;
   
-  
-  let normalize_weights (cw1, wl1) (cw2, wl2) =
-    let rec aux wl1 wl2 =
-      match wl1, wl2 with
-      | [], [] -> [], []
-      | (m, w)::tl1, (n, w')::tl2 when m = n ->
-          let res1, res2 = aux tl1 tl2 in
-          (m, w)::res1, (n, w')::res2
-      | (m, w)::tl1, ((n, w')::_ as wl2) when m < n ->
-          let res1, res2 = aux tl1 wl2 in
-          (m, w)::res1, (m, 0)::res2
-      | ((m, w)::_ as wl1), (n, w')::tl2 when m > n ->
-          let res1, res2 = aux wl1 tl2 in
-          (n, 0)::res1, (n, w')::res2
-      | [], (n, w)::tl2 ->
-          let res1, res2 = aux [] tl2 in
-          (n, 0)::res1, (n, w)::res2
-      | (m, w)::tl1, [] ->
-          let res1, res2 = aux tl1 [] in
-          (m, w)::res1, (m, 0)::res2
-      | _, _ -> assert false
+  let compute_unit_clause_weight (_,l, _, _) = 
+    let weight_of_polynomial w m =
+      let factor = 2 in      
+      w + factor * List.fold_left (fun acc (_,occ) -> acc+occ) 0 m
     in
-    let cmp (m, _) (n, _) = compare m n in
-    let wl1, wl2 = aux (List.sort cmp wl1) (List.sort cmp wl2) in
-    (cw1, wl1), (cw2, wl2)
+    match l with
+    | Terms.Predicate t -> 
+        let w, m = weight_of_term t in 
+        weight_of_polynomial w m
+    | Terms.Equation (_,x,_,Terms.Lt) 
+    | Terms.Equation (x,_,_,Terms.Gt) ->
+        let w, m = weight_of_term x in 
+        weight_of_polynomial w m
+    | Terms.Equation (l,r,_,Terms.Eq) 
+    | Terms.Equation (l,r,_,Terms.Incomparable) ->
+        let wl, ml = weight_of_term l in 
+        let wr, mr = weight_of_term r in 
+        weight_of_polynomial (wl+wr) (ml@mr)
   ;;
   
   (* Riazanov: 3.1.5 pag 38 *)
-  (* TODO: optimize early detection of Terms.Incomparable case *)
+(* Compare weights normalized in a new way :
+ * Variables should be sorted from the lowest index to the highest
+ * Variables which do not occur in the term should not be present
+ * in the normalized polynomial
+ *)
   let compare_weights (h1, w1) (h2, w2) =
-    let res, diffs =
-      try
-        List.fold_left2
-          (fun ((lt, eq, gt), diffs) w1 w2 ->
-             match w1, w2 with
-             | (meta1, w1), (meta2, w2) when meta1 = meta2 ->
-                 let diffs = (w1 - w2) + diffs in 
-                 let r = compare w1 w2 in
-                 if r < 0 then (lt+1, eq, gt), diffs
-                 else if r = 0 then (lt, eq+1, gt), diffs
-                 else (lt, eq, gt+1), diffs
-             | _ -> assert false)
-          ((0, 0, 0), 0) w1 w2
-      with Invalid_argument _ -> assert false
+    let rec aux hdiff (lt, gt) diffs w1 w2 =
+      match w1, w2 with
+	| ((var1, w1)::tl1) as l1, (((var2, w2)::tl2) as l2) ->
+	    if var1 = var2 then
+	      let diffs = (w1 - w2) + diffs in
+	      let r = compare w1 w2 in
+	      let lt = lt or (r < 0) in
+	      let gt = gt or (r > 0) in
+		if lt && gt then XINCOMPARABLE else
+		  aux hdiff (lt, gt) diffs tl1 tl2
+	    else if var1 < var2 then
+	      if lt then XINCOMPARABLE else
+		aux hdiff (false,true) (diffs+w1) tl1 l2	
+	    else
+	      if gt then XINCOMPARABLE else
+		aux hdiff (true,false) (diffs-w2) l1 tl2
+	| [], (_,w2)::tl2 ->
+	    if gt then XINCOMPARABLE else
+	      aux hdiff (true,false) (diffs-w2) [] tl2
+	| (_,w1)::tl1, [] ->
+	    if lt then XINCOMPARABLE else
+	      aux hdiff (false,true) (diffs+w1) tl1 []
+	| [], [] ->
+	    if lt then
+	      if hdiff <= 0 then XLT
+              else if (- diffs) >= hdiff then XLE else XINCOMPARABLE
+	    else if gt then
+	      if hdiff >= 0 then XGT
+              else if diffs >= (- hdiff) then XGE else XINCOMPARABLE
+	    else
+	      if hdiff < 0 then XLT
+	      else if hdiff > 0 then XGT
+              else XEQ
     in
-    let hdiff = h1 - h2 in 
-    match res with
-    | (0, _, 0) ->
-        if hdiff < 0 then Terms.Lt
-        else if hdiff > 0 then Terms.Gt
-        else Terms.Eq 
-    | (m, _, 0) ->
-        if hdiff <= 0 then Terms.Lt
-        else if (- diffs) >= hdiff then Terms.Le else Terms.Incomparable
-    | (0, _, m) ->
-        if hdiff >= 0 then Terms.Gt
-        else if diffs >= (- hdiff) then Terms.Ge else Terms.Incomparable
-    | (m, _, n) when m > 0 && n > 0 -> Terms.Incomparable
-    | _ -> assert false 
+      aux (h1-h2) (false,false) 0 w1 w2
   ;;
   
-  
-  let rec aux_ordering t1 t2 =
+  (* Riazanov: p. 40, relation >>> 
+   * if head_only=true then it is not >>> but helps case 2 of 3.14 p 39 *)
+  let rec aux_ordering ?(head_only=false) t1 t2 =
     match t1, t2 with
+    (* We want to discard any identity equality. *
+     * If we give back XEQ, no inference rule    *
+     * will be applied on this equality          *)
+    | Terms.Var i, Terms.Var j when i = j ->
+	XEQ
+    (* 1. *)
     | Terms.Var _, _
-    | _, Terms.Var _ -> Terms.Incomparable
-  
+    | _, Terms.Var _ -> XINCOMPARABLE
+    (* 2.a *)
     | Terms.Leaf a1, Terms.Leaf a2 -> 
-        let cmp = Pervasives.compare a1 a2 in
-        if cmp = 0 then Terms.Eq else if cmp < 0 then Terms.Lt else Terms.Gt
-  
-    | Terms.Leaf _, Terms.Node _ -> Terms.Lt
-    | Terms.Node _, Terms.Leaf _ -> Terms.Gt
-  
+        let cmp = B.compare a1 a2 in
+        if cmp = 0 then XEQ else if cmp < 0 then XLT else XGT
+    | Terms.Leaf _, Terms.Node _ -> XLT
+    | Terms.Node _, Terms.Leaf _ -> XGT
+    (* 2.b *)
     | Terms.Node l1, Terms.Node l2 ->
         let rec cmp t1 t2 =
           match t1, t2 with
-          | [], [] -> Terms.Eq
-          | _, [] -> Terms.Gt
-          | [], _ -> Terms.Lt
+          | [], [] -> XEQ
+          | _, [] -> XGT
+          | [], _ -> XLT
           | hd1::tl1, hd2::tl2 ->
-              let o = aux_ordering hd1 hd2 in
-              if o = Terms.Eq then cmp tl1 tl2
-              else o
+              let o = aux_ordering ~head_only hd1 hd2 in
+              if o = XEQ && not head_only then cmp tl1 tl2 else o
         in
         cmp l1 l2
   ;;
   
+  (* Riazanov: p. 40, relation >_n *)
   let nonrec_kbo t1 t2 =
     let w1 = weight_of_term t1 in
     let w2 = weight_of_term t2 in
-    let w1, w2 = normalize_weights w1 w2 in
     match compare_weights w1 w2 with
-    | Terms.Le -> if aux_ordering t1 t2 = Terms.Lt then Terms.Lt else Terms.Incomparable
-    | Terms.Ge -> if aux_ordering t1 t2 = Terms.Gt then Terms.Gt else Terms.Incomparable
-    | Terms.Eq -> aux_ordering t1 t2
+    | XLE ->  (* this is .> *)
+        if aux_ordering t1 t2 = XLT then XLT else XINCOMPARABLE
+    | XGE -> 
+        if aux_ordering t1 t2 = XGT then XGT else XINCOMPARABLE
+    | XEQ -> aux_ordering t1 t2
     | res -> res
   ;;
   
-  (*
+  (* Riazanov: p. 38, relation > *)
   let rec kbo t1 t2 =
-    let aux = aux_ordering ~recursion:false in
-    let w1 = weight_of_term t1
-    and w2 = weight_of_term t2 in
+    let aux = aux_ordering ~head_only:true in
     let rec cmp t1 t2 =
       match t1, t2 with
-      | [], [] -> Terms.Eq
-      | _, [] -> Terms.Gt
-      | [], _ -> Terms.Lt
+      | [], [] -> XEQ
+      | _, [] -> XGT
+      | [], _ -> XLT
       | hd1::tl1, hd2::tl2 ->
-          let o =
-            kbo hd1 hd2
-          in
-          if o = Terms.Eq then cmp tl1 tl2
+          let o = kbo hd1 hd2 in
+          if o = XEQ then cmp tl1 tl2
           else o
     in
-    let w1, w2 = normalize_weights w1 w2 in
+    let w1 = weight_of_term t1 in
+    let w2 = weight_of_term t2 in
     let comparison = compare_weights w1 w2 in
     match comparison with
-    | Terms.Le ->
+    | XLE ->
         let r = aux t1 t2 in
-        if r = Terms.Lt then Terms.Lt
-        else if r = Terms.Eq then (
+        if r = XLT then XLT
+        else if r = XEQ then (
           match t1, t2 with
-          | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
-              if cmp tl1 tl2 = Terms.Lt then Terms.Lt else Terms.Incomparable
-          | _, _ ->  Terms.Incomparable
-        ) else Terms.Incomparable
-    | Terms.Ge ->
+          | Terms.Node (_::tl1), Terms.Node (_::tl2) ->
+              if cmp tl1 tl2 = XLT then XLT else XINCOMPARABLE
+          | _, _ -> assert false
+        ) else XINCOMPARABLE
+    | XGE ->
         let r = aux t1 t2 in
-        if r = Terms.Gt then Terms.Gt
-        else if r = Terms.Eq then (
+        if r = XGT then XGT
+        else if r = XEQ then (
           match t1, t2 with
-          | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
-              if cmp tl1 tl2 = Terms.Gt then Terms.Gt else Terms.Incomparable
-          | _, _ ->  Terms.Incomparable
-        ) else Terms.Incomparable
-    | Terms.Eq ->
+          | Terms.Node (_::tl1), Terms.Node (_::tl2) ->
+              if cmp tl1 tl2 = XGT then XGT else XINCOMPARABLE
+          | _, _ ->  assert false
+        ) else XINCOMPARABLE
+    | XEQ ->
         let r = aux t1 t2 in
-        if r = Terms.Eq then (
+        if r = XEQ then (
           match t1, t2 with
-          | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
-              cmp tl1 tl2
-          | _, _ ->  Terms.Incomparable
+          | Terms.Node (_::tl1), Terms.Node (_::tl2) -> cmp tl1 tl2
+          | _, _ ->  XINCOMPARABLE
         ) else r 
     | res -> res
   ;;
-  *)
             
-  let compare_terms = nonrec_kbo;; 
+  let compare_terms x y = 
+    match nonrec_kbo x y with
+    | XINCOMPARABLE -> Terms.Incomparable
+    | XGT -> Terms.Gt
+    | XLT -> Terms.Lt
+    | XEQ -> Terms.Eq
+    | _ -> assert false
+  ;; 
 
 end