- let compare_weights (h1, w1) (h2, w2) =
- 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
- aux (h1-h2) (false,false) 0 w1 w2
- ;;
+let compare_weights (h1, w1) (h2, w2) =
+ 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 = Pervasives.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
+ aux (h1-h2) (false,false) 0 w1 w2
+;;
+
+(* 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 b_compare ?(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 _ -> XINCOMPARABLE
+ (* 2.a *)
+ | Terms.Leaf a1, Terms.Leaf a2 ->
+ 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
+ | [], [] -> XEQ
+ | _, [] -> (* XGT *) assert false (* hd symbols were eq *)
+ | [], _ -> (* XLT *) assert false (* hd symbols were eq *)
+ | hd1::tl1, hd2::tl2 ->
+ let o = aux_ordering b_compare ~head_only hd1 hd2 in
+ if o = XEQ && not head_only then cmp tl1 tl2 else o
+ in
+ cmp l1 l2
+;;