Determination of General Concept in Learning Default Rules

In this paper, we discuss a method to determine which concept, the target concept or its opposite, is more general in given examples when learning rules with exceptions, or default rules in the Inductive Logic Programming (ILP) framework. The ILP system learning default rules has to learn both the concepts in a three valued setting which clearly distinguishes what is true, what is false, and what is unknown. In order to learn hypotheses which holds as generally as possible in the domain, we should give a higher priority to the concept which is more general, or covers more examples than does the other. For this purpose, our method dynamically determines the general concept according to the ratio of positive examples covered by the hypothesis which is correct and most general in the hypothesis space.