clp like interface to gecode

library/gecode/clp_examples/photo.yap

@@ -0,0 +1,68 @@
+%% -*- prolog -*-
+%%=============================================================================
+%% Copyright (C) 2011 by Denys Duchier
+%%
+%% This program is free software: you can redistribute it and/or modify it
+%% under the terms of the GNU Lesser General Public License as published by the
+%% Free Software Foundation, either version 3 of the License, or (at your
+%% option) any later version.
+%% 
+%% This program is distributed in the hope that it will be useful, but WITHOUT
+%% ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+%% FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+%% more details.
+%% 
+%% You should have received a copy of the GNU Lesser General Public License
+%% along with this program.  If not, see <http://www.gnu.org/licenses/>.
+%%=============================================================================
+
+:- use_module(library(gecode/clpfd)).
+:- use_module(library(maplist)).
+
+% 5 people want to have a photograph together, but they have preferences.
+photo(Ex, Solution,Amount) :-
+	db(Ex, People, Preferences),
+	length(People, Len),
+	Len0 is Len-1,
+	People ins 0..Len0,
+	all_distinct(People),
+	% Bools are the satisfied constraints
+	maplist(preferences, Preferences, Bools),
+	length(Preferences, PLen),
+	Sum in 0..PLen,
+	Bools #= Sum,
+	% add all satisfied constraints
+	maximize(Sum),
+	labeling([], People).
+
+%reification, use with care
+preferences(X-Y, B) :-
+	abs(X - Y) #= 1 #<==> B.
+
+db(s,[Alice,Bob,Carl,Deb,Evan], [Alice-Carl,
+		Carl-Deb,
+		Deb-Alice,
+		Evan-Alice,
+		Bob-Evan,
+		Carl-Evan,
+		Deb-Evan,
+		Evan-Bob]).
+
+db(l,[Betty,Chris,Donald,Fred,Gary,Mary,Paul,Peter,Susan],
+	[Betty-Donald,
+	 Betty-Gary,
+	 Betty-Peter,
+	 Chris-Gary,
+	 Chris-Susan,
+	 Donald-Fred,
+	 Donald-Gary,
+	 Fred-Betty,
+	 Fred-Gary,
+	 Gary-Mary,
+	 Gary-Betty,
+	 Mary-Betty,
+	 Mary-Susan,
+	 Paul-Donald,
+	 Paul-Peter,
+	 Peter-Susan,
+	 Peter-Paul]).

library/gecode/clp_examples/queens.yap

@@ -1,12 +1,28 @@
 
+:- use_module(library(gecode/clpfd)).
 :- use_module(library(maplist)).
-:- [ge_clpfd].
 
 queens(N, Queens) :-
 	length(Queens, N),
-	Queens ins 1..9,
+	Queens ins 1..N,
 	all_distinct(Queens),
-	lconstrain( Queens, 0),
+	foldl(inc, Queens, Inc, 0, _), % [0, 1, 2, .... ]
+	foldl(dec, Queens, Dec, 0, _), % [0, -1, -2, ... ]
+	all_distinct(Inc,Queens),
+	all_distinct(Dec,Queens),
+	labeling([], Queens).
+
+inc(_, I0, I0, I) :-
+	I is I0+1.
+
+dec(_, I0, I0, I) :-
+	I is I0-1.
+
+lqueens(N, Queens) :-
+	length(Queens, N),
+	Queens ins 1..N,
+	all_distinct(Queens),
+	lconstrain( Queens, 0 ),
 	labeling([], Queens).
 
 lconstrain([], _).
@@ -19,3 +35,4 @@ constrain(Q, I, R, J, J1) :-
 	J1 is J+1,
 	Q + I #\= R + J,
 	Q - I #\= R - J.
+