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.data;
  
  import edu.cmu.tetrad.graph.IndependenceFact;
  import edu.cmu.tetrad.graph.Node;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Stores a list of independence facts.
   *
   * @author Joseph Ramsey
   */
  public class IndependenceFacts implements DataModel {
      static final long serialVersionUID = 23L;
  
      private Set<IndependenceFact> unsortedFacts = new HashSet<>();
      private String name = "";
      private IKnowledge knowledge = new Knowledge2();
  
      public IndependenceFacts() {
          // blank
      }
  
      public void add(IndependenceFact fact) {
          this.unsortedFacts.add(fact);
      }
  
      public IndependenceFacts(IndependenceFacts facts) {
          this();
          this.unsortedFacts = new HashSet<>(facts.unsortedFacts);
      }
  
      /**
       * Generates a simple exemplar of this class to test serialization.
       */
      public static IndependenceFacts serializableInstance() {
          return new IndependenceFacts();
      }
  
      public String toString() {
          StringBuilder builder = new StringBuilder();
  
          for (IndependenceFact fact : unsortedFacts) {
              builder.append(fact).append("\n");
          }
  
          return builder.toString();
      }
  
      @Override
      public boolean isContinuous() {
          return false;
      }
  
      @Override
      public boolean isDiscrete() {
          return false;
      }
  
      @Override
      public boolean isMixed() {
          return false;
      }
  
      @Override
      public Node getVariable(String name) {
          return null;
      }
  
      @Override
      public DataModel copy() {
          return null;
      }
  
      public void remove(IndependenceFact fact) {
  //        this.facts.remove(fact);
          this.unsortedFacts.remove(fact);
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public String getName() {
          return this.name;
      }
  
      public boolean isIndependent(Node x, Node y, Node... z) {
          IndependenceFact fact = new IndependenceFact(x, y, z);
          return unsortedFacts.contains(fact);
      }
  
      public boolean isIndependent(Node x, Node y, List<Node> z) {
          IndependenceFact fact = new IndependenceFact(x, y, z);
          System.out.println("Looking up " + fact + " in " + unsortedFacts);
          return unsortedFacts.contains(fact);
      }
  
      public IKnowledge getKnowledge() {
          return this.knowledge;
      }
  
      public void setKnowledge(IKnowledge knowledge) {
          if (knowledge == null) throw new NullPointerException();
          this.knowledge = knowledge;
      }
  
      public List<Node> getVariables() {
          Set<Node> variables = new HashSet<>();
  
          for (IndependenceFact fact : unsortedFacts) {
              variables.add(fact.getX());
              variables.add(fact.getY());
  
              for (Node z : fact.getZ()) {
                  variables.add(z);
              }
          }
  
          return new ArrayList<>(variables);
      }
  
      public List<String> getVariableNames() {
          List<Node> variables = getVariables();
          List<String> names = new ArrayList<>();
  
          for (Node node : variables) {
              names.add(node.getName());
          }
  
          return names;
      }
  }
  
  
  
  