/*******************************************************************************
* 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.minisat.constraints.card;
import java.io.Serializable;
import org.sat4j.minisat.constraints.cnf.Lits;
import org.sat4j.minisat.core.Constr;
import org.sat4j.minisat.core.ILits;
import org.sat4j.minisat.core.Undoable;
import org.sat4j.minisat.core.UnitPropagationListener;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.IVecInt;
/**
* Cardinality constraint.
*
* @author leberre
*/
public class AtLeast implements Constr, Undoable, Serializable {
private static final long serialVersionUID = 1L;
/** number of allowed falsified literal */
protected int maxUnsatisfied;
/** current number of falsified literals */
private int counter;
/**
* constraint literals
*/
protected final int[] lits;
protected final ILits voc;
/**
* @param ps
* a vector of literals
* @param degree
* the minimal number of satisfied literals
*/
protected AtLeast(ILits voc, IVecInt ps, int degree) {
maxUnsatisfied = ps.size() - degree;
this.voc = voc;
counter = 0;
lits = new int[ps.size()];
ps.moveTo(lits);
for (int q : lits) {
voc.attach(q ^ 1, this);
}
}
public static AtLeast atLeastNew(UnitPropagationListener s, ILits voc,
IVecInt ps, int n) throws ContradictionException {
int degree = Cards.niceParameters(s, voc, ps, n);
if (degree == 0)
return null;
return new AtLeast(voc, ps, degree);
}
/*
* (non-Javadoc)
*
* @see Constr#remove(Solver)
*/
public void remove() {
for (int q : lits) {
voc.attaches(q ^ 1).remove(this);
}
}
/*
* (non-Javadoc)
*
* @see Constr#propagate(Solver, Lit)
*/
public boolean propagate(UnitPropagationListener s, int p) {
// remet la clause dans la liste des clauses regardees
voc.attach(p, this);
if (counter == maxUnsatisfied)
return false;
counter++;
voc.undos(p).push(this);
// If no more can be false, enqueue the rest:
if (counter == maxUnsatisfied)
for (int q : lits) {
if (voc.isUnassigned(q) && !s.enqueue(q, this)) {
return false;
}
}
return true;
}
/*
* (non-Javadoc)
*
* @see Constr#simplify(Solver)
*/
public boolean simplify() {
return false;
}
/*
* (non-Javadoc)
*
* @see Constr#undo(Solver, Lit)
*/
public void undo(int p) {
counter--;
}
/*
* (non-Javadoc)
*
* @see Constr#calcReason(Solver, Lit, Vec)
*/
public void calcReason(int p, IVecInt outReason) {
int c = (p == ILits.UNDEFINED) ? -1 : 0;
for (int q : lits) {
if (voc.isFalsified(q)) {
outReason.push(q ^ 1);
if (++c == maxUnsatisfied)
return;
}
}
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.datatype.Constr#learnt()
*/
public boolean learnt() {
// Ces contraintes ne sont pas apprises pour le moment.
return false;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.datatype.Constr#getActivity()
*/
public double getActivity() {
// TODO Auto-generated method stub
return 0;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.datatype.Constr#incActivity(double)
*/
public void incActivity(double claInc) {
// TODO Auto-generated method stub
}
/*
* For learnt clauses only @author leberre
*/
public boolean locked() {
// FIXME need to be adapted to AtLeast
// return lits[0].getReason() == this;
return true;
}
public void setLearnt() {
throw new UnsupportedOperationException();
}
public void register() {
throw new UnsupportedOperationException();
}
public int size() {
return lits.length;
}
public int get(int i) {
return lits[i];
}
public void rescaleBy(double d) {
throw new UnsupportedOperationException();
}
public void assertConstraint(UnitPropagationListener s) {
throw new UnsupportedOperationException();
}
/**
* Cha?ne repr?sentant la contrainte
*
* @return Cha?ne repr?sentant la contrainte
*/
@Override
public String toString() {
StringBuffer stb = new StringBuffer();
stb.append("Card (" + lits.length + ") : ");
for (int i = 0; i < lits.length; i++) {
// if (voc.isUnassigned(lits[i])) {
stb.append(" + "); //$NON-NLS-1$
stb.append(Lits.toString(this.lits[i]));
stb.append("[");
stb.append(voc.valueToString(lits[i]));
stb.append("@");
stb.append(voc.getLevel(lits[i]));
stb.append("]");
stb.append(" ");
stb.append(" "); //$NON-NLS-1$
}
stb.append(">= "); //$NON-NLS-1$
stb.append(size() - maxUnsatisfied);
return stb.toString();
}
}