code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
  //	
  //------------------------------------------------------------------------------
  //	
  //	This file is part of PRISM.
  //	
  //	PRISM is free software; you can redistribute it and/or modify
  //	it under the terms of the GNU General Public License as published by
  //	the Free Software Foundation; either version 2 of the License, or
  //	(at your option) any later version.
  //	
  //	PRISM is distributed in the hope that it will be useful,
  //	but WITHOUT ANY WARRANTY; without even the implied warranty of
  //	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //	GNU General Public License for more details.
  //	
  //	You should have received a copy of the GNU General Public License
  //	along with PRISM; if not, write to the Free Software Foundation,
  //	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //	
  //==============================================================================
  
  package prism;
  
  import jdd.JDDNode;
  import parser.Values;
  import parser.ast.*;
  
  // interface for model checker classes
  
  public interface ModelChecker
  {
  	/**
  	 * Model check an expression, process, print and return the result.
  	 */
  	public Result check(Expression expr) throws PrismException;
  
  	/**
  	 * Model check an expression and return a vector of result values,
  	 * with valid results for at least all states of interest.
  	 *
  	 * @param expr the expression
  	 * @param statesOfInterest the states of interest.
  	 * <br>[ REFS: <i>result</i>, DEREFS: statesOfInterest ]
  	 */
  	public StateValues checkExpression(Expression expr, JDDNode statesOfInterest) throws PrismException;
  
  	/**
  	 * Model check expression, convert to symbolic form (if not already), return BDD.
  	 * <br>
  	 * Will have valid results at least for all states of interest.
  	 * @param expr the expression
  	 * @param statesOfInterest the states of interest
  	 * <br>[ REFS: <i>result</i>, DEREFS: statesOfInterest ]
  	 */
  	public JDDNode checkExpressionDD(Expression expr, JDDNode statesOfInterest) throws PrismException;
  
  	/** Get the constant values (both from the modules file and the properties file) */
  	public Values getConstantValues();
  }
  
  //------------------------------------------------------------------------------
  