/*******************************************************************************
* 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.specs;
import java.io.PrintWriter;
/**
* Access to the information related to a given problem instance.
*
* @author leberre
*/
public interface IProblem {
/**
* Provide a model (if any) for a satisfiable formula. That method should be
* called AFTER isSatisfiable() or isSatisfiable(IVecInt) if the formula is
* satisfiable. Else an exception UnsupportedOperationException is launched.
*
* @return a model of the formula as an array of literals to satisfy.
* @see #isSatisfiable()
* @see #isSatisfiable(IVecInt)
*/
int[] model();
/**
* Provide the truth value of a specific variable in the model. That method
* should be called AFTER isSatisfiable() if the formula is satisfiable.
* Else an exception UnsupportedOperationException is launched.
*
* @param var
* the variable id in Dimacs format
* @return the truth value of that variable in the model
* @since 1.6
* @see #model()
*/
boolean model(int var);
/**
* Check the satisfiability of the set of constraints contained inside the
* solver.
*
* @return true if the set of constraints is satisfiable, else false.
*/
boolean isSatisfiable() throws TimeoutException;
/**
* Check the satisfiability of the set of constraints contained inside the
* solver.
*
* @param assumps
* a set of literals (represented by usual non null integers
* in Dimacs format).
* @param globalTimeout
* whether that call is part of a global process (i.e.
* optimization) or not. if (global), the timeout will not be
* reset between each call.
* @return true if the set of constraints is satisfiable when literals are
* satisfied, else false.
*/
boolean isSatisfiable(IVecInt assumps, boolean globalTimeout)
throws TimeoutException;
/**
* Check the satisfiability of the set of constraints contained inside the
* solver.
*
* @param globalTimeout
* whether that call is part of a global process (i.e.
* optimization) or not. if (global), the timeout will not be
* reset between each call.
* @return true if the set of constraints is satisfiable, else false.
*/
boolean isSatisfiable(boolean globalTimeout) throws TimeoutException;
/**
* Check the satisfiability of the set of constraints contained inside the
* solver.
*
* @param assumps
* a set of literals (represented by usual non null integers
* in Dimacs format).
* @return true if the set of constraints is satisfiable when literals are
* satisfied, else false.
*/
boolean isSatisfiable(IVecInt assumps) throws TimeoutException;
/**
* Look for a model satisfying all the clauses available in the problem. It
* is an alternative to isSatisfiable() and model() methods, as shown in the
* pseudo-code: <code>
if (isSatisfiable()) {
return model();
}
return null;
</code>
*
* @return a model of the formula as an array of literals to satisfy, or
* <code>null</code> if no model is found
* @throws TimeoutException
* if a model cannot be found within the given timeout.
* @since 1.7
*/
int[] findModel() throws TimeoutException;
/**
* Look for a model satisfying all the clauses available in the problem. It
* is an alternative to isSatisfiable(IVecInt) and model() methods, as shown
* in the pseudo-code: <code>
if (isSatisfiable(assumpt)) {
return model();
}
return null;
</code>
*
* @return a model of the formula as an array of literals to satisfy, or
* <code>null</code> if no model is found
* @throws TimeoutException
* if a model cannot be found within the given timeout.
* @since 1.7
*/
int[] findModel(IVecInt assumps) throws TimeoutException;
/**
* To know the number of constraints currently available in the solver.
* (without taking into account learned constraints).
*
* @return the number of constraints added to the solver
*/
int nConstraints();
/**
* To know the number of variables used in the solver.
*
* @return the number of variables created using newVar().
*/
int nVars();
/**
* To print additional informations regarding the problem.
*
* @param out
* the place to print the information
* @param prefix
* the prefix to put in front of each line
*/
void printInfos(PrintWriter out, String prefix);
}