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The pb library contains algorithms for solving pseudo boolean optimization problems.
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/*******************************************************************************
 * 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 pseudo boolean algorithms described in:
 * A fast pseudo-Boolean constraint solver Chai, D.; Kuehlmann, A.
 * Computer-Aided Design of Integrated Circuits and Systems, IEEE Transactions on
 * Volume 24, Issue 3, March 2005 Page(s): 305 - 317
 * 
 * and 
 * Heidi E. Dixon, 2004. Automating Pseudo-Boolean Inference within a DPLL 
 * Framework. Ph.D. Dissertation, University of Oregon.
 *******************************************************************************/
package org.sat4j.pb;

import org.sat4j.core.VecInt;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.IOptimizationProblem;
import org.sat4j.specs.IVecInt;
import org.sat4j.specs.TimeoutException;

/**
 * Utility class to use optimization solvers instead of simple SAT solvers in
 * code meant for SAT solvers.
 * 
 * @author daniel
 */
public class OptToPBSATAdapter extends PBSolverDecorator {

	/**
     * 
     */
	private static final long serialVersionUID = 1L;

	IOptimizationProblem problem;

	boolean modelComputed = false;

	private final IVecInt assumps = new VecInt();

	private long begin;

	public OptToPBSATAdapter(IOptimizationProblem problem) {
		super((IPBSolver) problem);
		this.problem = problem;
	}

	@Override
	public boolean isSatisfiable() throws TimeoutException {
		modelComputed = false;
		assumps.clear();
		begin = System.currentTimeMillis();
		if (problem.hasNoObjectiveFunction()) {
			return modelComputed = problem.isSatisfiable();
		}
		return problem.admitABetterSolution();
	}

	@Override
	public boolean isSatisfiable(boolean global) throws TimeoutException {
		return isSatisfiable();
	}

	@Override
	public boolean isSatisfiable(IVecInt myAssumps, boolean global)
			throws TimeoutException {
		return isSatisfiable(myAssumps);
	}

	@Override
	public boolean isSatisfiable(IVecInt myAssumps) throws TimeoutException {
		modelComputed = false;
		this.assumps.clear();
		myAssumps.copyTo(this.assumps);
		begin = System.currentTimeMillis();
		if (problem.hasNoObjectiveFunction()) {
			return modelComputed = problem.isSatisfiable(myAssumps);
		}
		return problem.admitABetterSolution(myAssumps);
	}

	@Override
	public int[] model() {
		if (modelComputed)
			return problem.model();
		try {
			assert problem.admitABetterSolution(assumps);
			assert !problem.hasNoObjectiveFunction();
			do {
				problem.discardCurrentSolution();
				if (isVerbose()) {
					System.out.println(getLogPrefix()
							+ "Current objective function value: "
							+ problem.getObjectiveValue() + "("
							+ ((System.currentTimeMillis() - begin) / 1000.0)
							+ "s)");
				}
			} while (problem.admitABetterSolution(assumps));
		} catch (TimeoutException e) {
			if (isVerbose()) {
				System.out.println(getLogPrefix() + "Solver timed out after "
						+ ((System.currentTimeMillis() - begin) / 1000.0)
						+ "s)");
			}
		} catch (ContradictionException e) {
			// OK, optimal model found
		}
		modelComputed = true;
		return problem.model();
	}

	@Override
	public boolean model(int var) {
		if (!modelComputed)
			model();
		return problem.model(var);
	}

	@Override
	public String toString(String prefix) {
		return prefix + "Optimization to Pseudo Boolean adapter\n"
				+ super.toString(prefix);
	}

	public boolean isOptimal() {
		return problem.isOptimal();
	}
}