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