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.search;
  
  import edu.cmu.tetrad.graph.*;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Given a pattern this class implements two algortithms for finding an associated directed acyclic graph (DAG).
   * <p>
   * The first algorithm (in patternToDagMeek) was described in Zhang and Spirtes (2005), "A Characterization of Markov
   * Equivalence Classes for Ancestral Graphical Models" on pp. 53-54.
   * <p>
   * The second algorithm (in patternToDagDorTarsi) was described by Chickering (2002) in "Optimal Structure
   * Identification with Greedy Search" in the Journal of Machine Learning Research.  The algorithm was proposed by Dor
   * and Tarsi (1992).
   *
   * @author Frank Wimberly
   */
  public class PatternToDag {
  
      /**
       * The input pattern
       */
      private Graph pattern;
  
      //=============================CONSTRUCTORS==========================//
  
      public PatternToDag(Graph pattern) {
          if (pattern == null) {
              throw new IllegalArgumentException(
                      "Input pattern must not be null");
          }
  
          this.pattern = pattern;
      }
  
      /**
       * This algorithm is due to Meek (1995) and was described by Zhang and Spirtes (2005), "A Characterization of Markov
       * Equivalence Classes for Ancestral Graphical Models" on pp. 53-54.
       */
      public Graph patternToDagMeek() {
          return SearchGraphUtils.dagFromPattern(pattern);
      }
  }
  
  
  
  
  