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yap-6.3/packages/gecode/examples/photo.yap
2013-11-03 14:12:38 +00:00

81 lines
2.3 KiB
Prolog

%% -*- 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)).
:- use_module(library(maplist)).
% 5 people want to have a photograph together, but they have preferences.
photo(Ex, Solution,Amount) :-
db(Ex, People, Preferences),
Space := space,
length(People, Len),
Len0 is Len-1,
People := intvars(Space,Len,0,Len0),
Space += distinct(People),
% Bools are the satisfied constraints
maplist(preferences(Space, Len), Preferences, Bools),
length(Preferences, PLen),
Sum := intvar(Space,0,PLen),
Space += linear(Bools,'IRT_EQ',Sum),
% add all satisfied constraints
Space += maximize(Sum),
Space += branch(People,'INT_VAR_SIZE_MIN','INT_VAL_MIN'),
SolSpace := search(Space),
Solution := val(SolSpace,People),
Amount := val(SolSpace,Sum).
%reification, use with care
preferences(Space, Len, X-Y, B) :-
NLen is -Len,
I0 := intvar(Space, NLen, Len),
I := intvar(Space, 0, Len),
B := boolvar(Space),
Space += reify(B, 'RM_EQV', R),
Space += linear([1,-1],[X,Y],'IRT_EQ', I0),
Space += abs(I0, I),
Space += rel(I, 'IRT_EQ', 1, R).
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]).