001 package aima.learning.knowledge;
002
003 import java.util.List;
004
005 import aima.logic.fol.kb.FOLKnowledgeBase;
006 import aima.logic.fol.kb.data.Clause;
007
008 /**
009 * Artificial Intelligence A Modern Approach (2nd Edition): Figure 19.2, page 681.
010 *
011 * <code>
012 * function CURRENT-BEST-LEARNING(examples) returns a hypothesis
013 *
014 * H <- any hypothesis consistent with the first example in examples.
015 * for each remaining example in examples do
016 * if e is false positive for H then
017 * H <- choose a specialization of H consistent with examples
018 * else if e is false negative for H then
019 * H <- choose a generalization of H consistent with examples
020 * if no consistent specialization/generalization can be found then fail
021 * return H
022 * </code>
023 *
024 * Figure 19.2 The current-best-hypothesis learning algorithm. It searches for a consistent
025 * hypothesis and backtracks when no consistent specialization/generalization can be found.
026 */
027
028 /**
029 * @author Ciaran O'Reilly
030 *
031 */
032 public class CurrentBestLearning {
033 private FOLDataSetDomain folDSDomain = null;
034 private FOLKnowledgeBase kbForLearning = null;
035
036 //
037 // PUBLIC METHODS
038 //
039 public CurrentBestLearning(FOLDataSetDomain folDSDomain, FOLKnowledgeBase kbForLearning) {
040 this.folDSDomain = folDSDomain;
041 this.kbForLearning = kbForLearning;
042 }
043
044 // * function CURRENT-BEST-LEARNING(examples) returns a hypothesis
045 public Hypothesis currentBestLearning(List<FOLExample> examples) {
046
047 // TODO-use the default from pg 679 for now.
048 String c1 = "patrons(v,Some)";
049 String c2 = "patrons(v,Full) AND (hungry(v) AND type(v,French))";
050 String c3 = "patrons(v,Full) AND (hungry(v) AND (type(v,Thai) AND fri_sat(v)))";
051 String c4 = "patrons(v,Full) AND (hungry(v) AND type(v,Burger))";
052 String sh = "FORALL v (will_wait(v) <=> ("+c1+" OR ("+c2+" OR ("+c3+" OR ("+c4+")))))";
053
054 Hypothesis H = new Hypothesis(kbForLearning.tell(sh));
055
056 // TODO
057 // * H <- any hypothesis consistent with the first example in examples.
058 // * for each remaining example in examples do
059 // * if e is false positive for H then
060 // * H <- choose a specialization of H consistent with examples
061 // * else if e is false negative for H then
062 // * H <- choose a generalization of H consistent with examples
063 // * if no consistent specialization/generalization can be found then
064 // fail
065 // * return H
066 return H;
067 }
068
069 //
070 // PRIVATE METHODS
071 //
072 }