Figure 2

Interesting cases when evaluating hierarchical classifiers: (a) over-specialization, (b) under-specialization, (c) alternative problems, (d) pairing problem, (e) long distance problem. Nodes surrounded by circles are the true classes while the nodes surrounded by rectangles are the predicted classes. LCaF ia based on the notion of adding all ancestors of the predicted (rectangles) and true (circles) classes. However, adding all the ancestors has the undesirable effect of over-penalizing errors that happen to nodes with many ancestors. Thus, LCaF uses the notion of the Lowest Common Ancestor to limit the addition of ancestors.