code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program 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.                                       //
  //                                                                           //
  // This program 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 this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.bayes;
  
  import edu.cmu.tetrad.graph.Node;
  
  import java.util.List;
  
  /**
   * Interface containing methods to calculate probabilities for systems of
   * discrete variables. See instantiations for more details.
   *
   * @author Joseph Ramsey
   */
  interface DiscreteProbs {
  
      /**
       * @return the variables over which probabilities and conditional
       * probabilities will be calculated.
       */
      List<Node> getVariables();
  
      /**
       * @return the probability in a given cell.
       */
      double getCellProb(int[] cell);
  
      /**
       * Calculates the probability P(a), where a is a two dimensional boolean
       * array, with a[i] representing particular combinations of values for
       * bayesIm.getNode(i) as boolean arrays of length bayesim.getNumSplits(i),
       * with a[i][j] = true iff the condition includes the j'th value of
       * bayesIm.getNode(i).
       */
      double getProb(Proposition assertion);
  
      /**
       * <p>Calculates the conditional probability P(a|b), where a and b are two
       * dimensional boolean arrays, with a[i] and b[i] representing particular
       * combinations of values for bayesIm.getNode(i) as boolean arrays of length
       * bayesim.getNumSplits(i), with a[i][j] = true iff the condition
       * includes the j'th value of bayesIm.getNode(i), and similarly for
       * b[i][j].</p> </p> <p>This does not allow all possible conditional
       * probabilities to be calculated, since for instance the condition X1 = 1
       * or X2 = 2 cannot be represented this way directly, but it does capture
       * all conditions for which this type of method would generally be of
       * interest.</p>
       */
      double getConditionalProb(Proposition assertion, Proposition condition);
  
      /**
       * @return true if a missing values case was encountered during the last
       * method call.
       */
      boolean isMissingValueCaseFound();
  }
  
  
  
  
  
  