001    package net.sf.cpsolver.coursett.constraint;
002    
003    import net.sf.cpsolver.coursett.model.Placement;
004    
005    /**
006     * Interface of a constraint that weakens with the time.
007     * 
008     * @version CourseTT 1.2 (University Course Timetabling)<br>
009     *          Copyright (C) 2006 - 2010 Tomas Muller<br>
010     *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
011     *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
012     * <br>
013     *          This library is free software; you can redistribute it and/or modify
014     *          it under the terms of the GNU Lesser General Public License as
015     *          published by the Free Software Foundation; either version 3 of the
016     *          License, or (at your option) any later version. <br>
017     * <br>
018     *          This library is distributed in the hope that it will be useful, but
019     *          WITHOUT ANY WARRANTY; without even the implied warranty of
020     *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
021     *          Lesser General Public License for more details. <br>
022     * <br>
023     *          You should have received a copy of the GNU Lesser General Public
024     *          License along with this library; if not see
025     *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
026     */
027    
028    public interface WeakeningConstraint {
029        /**
030         * Weaken the constraint. This method is called if the constraint
031         * participates in an unassigned of a variable.
032         */
033        public void weaken();
034        
035        
036        /**
037         * Weaken the constraint enough so that it can assign the given
038         * value.
039         */
040        public void weaken(Placement value);
041    }