2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department, University of Bologna, Italy.
6 ||T|| HELM is free software; you can redistribute it and/or
7 ||A|| modify it under the terms of the GNU General Public License
8 \ / version 2 or (at your option) any later version.
9 \ / This software is distributed as is, NO WARRANTY.
10 V_______________________________________________________________ *)
14 module Orderings (B : Terms.Blob) = struct
16 type weight = int * (int * int) list;;
18 let string_of_weight (cw, mw) =
21 (List.map (function (m, w) -> Printf.sprintf "(%d,%d)" m w) mw)
23 Printf.sprintf "[%d; %s]" cw s
26 let weight_of_term term =
27 let vars_dict = Hashtbl.create 5 in
28 let rec aux = function
31 let oldw = Hashtbl.find vars_dict i in
32 Hashtbl.replace vars_dict i (oldw+1)
34 Hashtbl.add vars_dict i 1);
37 | Terms.Node l -> List.fold_left (+) 0 (List.map aux l)
41 Hashtbl.fold (fun meta metaw resw -> (meta, metaw)::resw) vars_dict []
45 | (m1, _), (m2, _) -> m2 - m1
47 (w, List.sort compare l) (* from the biggest meta to the smallest (0) *)
50 let compute_clause_weight = assert false (*
54 let w, m = (weight_of_term
55 ~consider_metas:true ~count_metas_occurrences:false right) in
56 w + (factor * (List.length m)) ;
57 | Terms.Le -> assert false
59 let w, m = (weight_of_term
60 ~consider_metas:true ~count_metas_occurrences:false left) in
61 w + (factor * (List.length m)) ;
62 | Terms.Ge -> assert false
64 | Terms.Incomparable ->
65 let w1, m1 = (weight_of_term
66 ~consider_metas:true ~count_metas_occurrences:false right) in
67 let w2, m2 = (weight_of_term
68 ~consider_metas:true ~count_metas_occurrences:false left) in
69 w1 + w2 + (factor * (List.length m1)) + (factor * (List.length m2))
73 (* returns a "normalized" version of the polynomial weight wl (with type
74 * weight list), i.e. a list sorted ascending by meta number,
75 * from 0 to maxmeta. wl must be sorted descending by meta number. Example:
76 * normalize_weight 5 (3, [(3, 2); (1, 1)]) ->
77 * (3, [(1, 1); (2, 0); (3, 2); (4, 0); (5, 0)]) *)
78 let normalize_weight maxmeta (cw, wl) =
79 let rec aux = function
81 | m -> (m, 0)::(aux (m-1))
83 let tmpl = aux maxmeta in
86 (fun (m, _) (n, _) -> Pervasives.compare m n)
88 (fun res (m, w) -> (m, w)::(List.remove_assoc m res)) tmpl wl)
94 let normalize_weights (cw1, wl1) (cw2, wl2) =
98 | (m, w)::tl1, (n, w')::tl2 when m = n ->
99 let res1, res2 = aux tl1 tl2 in
100 (m, w)::res1, (n, w')::res2
101 | (m, w)::tl1, ((n, w')::_ as wl2) when m < n ->
102 let res1, res2 = aux tl1 wl2 in
103 (m, w)::res1, (m, 0)::res2
104 | ((m, w)::_ as wl1), (n, w')::tl2 when m > n ->
105 let res1, res2 = aux wl1 tl2 in
106 (n, 0)::res1, (n, w')::res2
108 let res1, res2 = aux [] tl2 in
109 (n, 0)::res1, (n, w)::res2
111 let res1, res2 = aux tl1 [] in
112 (m, w)::res1, (m, 0)::res2
113 | _, _ -> assert false
115 let cmp (m, _) (n, _) = compare m n in
116 let wl1, wl2 = aux (List.sort cmp wl1) (List.sort cmp wl2) in
117 (cw1, wl1), (cw2, wl2)
120 (* Riazanov: 3.1.5 pag 38 *)
121 (* TODO: optimize early detection of Terms.Incomparable case *)
122 let compare_weights (h1, w1) (h2, w2) =
126 (fun ((lt, eq, gt), diffs) w1 w2 ->
128 | (meta1, w1), (meta2, w2) when meta1 = meta2 ->
129 let diffs = (w1 - w2) + diffs in
130 let r = compare w1 w2 in
131 if r < 0 then (lt+1, eq, gt), diffs
132 else if r = 0 then (lt, eq+1, gt), diffs
133 else (lt, eq, gt+1), diffs
136 with Invalid_argument _ -> assert false
138 let hdiff = h1 - h2 in
141 if hdiff < 0 then Terms.Lt
142 else if hdiff > 0 then Terms.Gt
145 if hdiff <= 0 then Terms.Lt
146 else if (- diffs) >= hdiff then Terms.Le else Terms.Incomparable
148 if hdiff >= 0 then Terms.Gt
149 else if diffs >= (- hdiff) then Terms.Ge else Terms.Incomparable
150 | (m, _, n) when m > 0 && n > 0 -> Terms.Incomparable
155 let rec aux_ordering t1 t2 =
158 | _, Terms.Var _ -> Terms.Incomparable
160 | Terms.Leaf a1, Terms.Leaf a2 ->
161 let cmp = Pervasives.compare a1 a2 in
162 if cmp = 0 then Terms.Eq else if cmp < 0 then Terms.Lt else Terms.Gt
164 | Terms.Leaf _, Terms.Node _ -> Terms.Lt
165 | Terms.Node _, Terms.Leaf _ -> Terms.Gt
167 | Terms.Node l1, Terms.Node l2 ->
173 | hd1::tl1, hd2::tl2 ->
174 let o = aux_ordering hd1 hd2 in
175 if o = Terms.Eq then cmp tl1 tl2
181 let nonrec_kbo t1 t2 =
182 let w1 = weight_of_term t1 in
183 let w2 = weight_of_term t2 in
184 let w1, w2 = normalize_weights w1 w2 in
185 match compare_weights w1 w2 with
186 | Terms.Le -> if aux_ordering t1 t2 = Terms.Lt then Terms.Lt else Terms.Incomparable
187 | Terms.Ge -> if aux_ordering t1 t2 = Terms.Gt then Terms.Gt else Terms.Incomparable
188 | Terms.Eq -> aux_ordering t1 t2
194 let aux = aux_ordering ~recursion:false in
195 let w1 = weight_of_term t1
196 and w2 = weight_of_term t2 in
202 | hd1::tl1, hd2::tl2 ->
206 if o = Terms.Eq then cmp tl1 tl2
209 let w1, w2 = normalize_weights w1 w2 in
210 let comparison = compare_weights w1 w2 in
211 match comparison with
214 if r = Terms.Lt then Terms.Lt
215 else if r = Terms.Eq then (
217 | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
218 if cmp tl1 tl2 = Terms.Lt then Terms.Lt else Terms.Incomparable
219 | _, _ -> Terms.Incomparable
220 ) else Terms.Incomparable
223 if r = Terms.Gt then Terms.Gt
224 else if r = Terms.Eq then (
226 | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
227 if cmp tl1 tl2 = Terms.Gt then Terms.Gt else Terms.Incomparable
228 | _, _ -> Terms.Incomparable
229 ) else Terms.Incomparable
232 if r = Terms.Eq then (
234 | Cic.Appl (h1::tl1), Cic.Appl (h2::tl2) when h1 = h2 ->
236 | _, _ -> Terms.Incomparable
242 let compare_terms = nonrec_kbo;;