Ch. 19 – Knowledge in Learning

1. Ch. 19 – Knowledge in Learning Supplemental slides for CSE 327 Prof. Jeff Heflin

2. Example Learning Problem (current best hypothesis search) Training Set Only consider candidate definitions that are positive conjunctive sentences

3. Current Best Hypothesis Search functionCurrent-Best-Learning(examples,h) returns a hypothesis or fail if examples is empty then return he First(examples)ife is consistent with hthenreturn Current-Best-Learning (Rest(examples),h)else if e is a false positive for hthen for each h’in specializations of h consistent with examples seen so far doh’’Current-Best-Learning (Rest(examples),h’)if h’’  fail then return h’’else if e is a false negative for hthen for each h’in generalizations of h consistent with examples seen so far doh’’Current-Best-Learning (Rest(examples),h’)if h’’  fail then return h’’returnfail From Figure 19.2, p. 771

4. Current-Best Hypothesis Search 1 True hypothesis X1: TP example: status 2 TP = true positive True TN = true negative X2: FP FP = false positive FN = false negative 3 Color(x,Red) Shape(x,Circle) X3: FP X3: ? 4 6 Color(x,Red)  Size(x,Large) Color(x,Red)  Shape(x,Circle) X4: TN X4: TN 5 Color(x,Red)  Size(x,Large) 7 Color(x,Red)  Shape(x,Circle) X5: FN X5: TP