1. A method comprising: storing information representing a hierarchy of categories; receiving, by at least one processor, an indication that a first case is either a positive case or a negative case for a first category in the hierarchy of categories; identifying, by inference by the at least one processor, the first case as a positive case or negative case for a second category in the hierarchy based on a relationship of the second category to the first category; and modifying a training set for the second category based on the identifying.