/*******************************************************************************
* SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU Lesser General Public License Version 2.1 or later (the
* "LGPL"), in which case the provisions of the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of the LGPL, and not to allow others to use your version of
* this file under the terms of the EPL, indicate your decision by deleting
* the provisions above and replace them with the notice and other provisions
* required by the LGPL. If you do not delete the provisions above, a recipient
* may use your version of this file under the terms of the EPL or the LGPL.
*
* Based on the original MiniSat specification from:
*
* An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
* Sixth International Conference on Theory and Applications of Satisfiability
* Testing, LNCS 2919, pp 502-518, 2003.
*
* See www.minisat.se for the original solver in C++.
*
*******************************************************************************/
package org.sat4j;
import java.io.PrintWriter;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.IOptimizationProblem;
import org.sat4j.specs.IProblem;
import org.sat4j.specs.TimeoutException;
/**
* This class is intended to be used by launchers to solve optimization
* problems, i.e. problems for which a loop is needed to find the optimal
* solution.
*
* @author leberre
*
*/
public abstract class AbstractOptimizationLauncher extends AbstractLauncher {
/**
*
*/
private static final long serialVersionUID = 1L;
private static final String CURRENT_OPTIMUM_VALUE_PREFIX = "o "; //$NON-NLS-1$
@Override
protected void displayResult() {
displayAnswer();
log("Total wall clock time (in seconds): " //$NON-NLS-1$
+ (System.currentTimeMillis() - getBeginTime()) / 1000.0);
}
protected void displayAnswer(){
if (solver == null)
return;
PrintWriter out = getLogWriter();
solver.printStat(out, COMMENT_PREFIX);
ExitCode exitCode = getExitCode();
out.println(ANSWER_PREFIX + exitCode);
if (exitCode == ExitCode.SATISFIABLE
|| exitCode == ExitCode.OPTIMUM_FOUND) {
out.print(SOLUTION_PREFIX);
getReader().decode(solver.model(), out);
out.println();
IOptimizationProblem optproblem = (IOptimizationProblem) solver;
if (!optproblem.hasNoObjectiveFunction()) {
log("objective function=" + optproblem.calculateObjective()); //$NON-NLS-1$
}
}
}
@Override
protected void solve(IProblem problem) throws TimeoutException {
boolean isSatisfiable = false;
IOptimizationProblem optproblem = (IOptimizationProblem) problem;
try {
while (optproblem.admitABetterSolution()) {
if (!isSatisfiable) {
if (optproblem.nonOptimalMeansSatisfiable()) {
setExitCode(ExitCode.SATISFIABLE);
if (optproblem.hasNoObjectiveFunction()) {
return;
}
log("SATISFIABLE"); //$NON-NLS-1$
}
isSatisfiable = true;
log("OPTIMIZING..."); //$NON-NLS-1$
}
log("Got one! Elapsed wall clock time (in seconds):" //$NON-NLS-1$
+ (System.currentTimeMillis() - getBeginTime())
/ 1000.0);
getLogWriter().println(
CURRENT_OPTIMUM_VALUE_PREFIX
+ optproblem.calculateObjective());
optproblem.discard();
}
if (isSatisfiable) {
setExitCode(ExitCode.OPTIMUM_FOUND);
} else {
setExitCode(ExitCode.UNSATISFIABLE);
}
} catch (ContradictionException ex) {
assert isSatisfiable;
setExitCode(ExitCode.OPTIMUM_FOUND);
}
}
}