Inductive Inference of Context-free Languages Based on Context-free Expressions

An inductive inference problem of context-free languages is considered. There have been many attempts to this problem, and most of them are based on a problem setup in which a representation space for hypotheses is a class of context-free grammars. An inference algorithm given in this paper, on the contrary, employs a kind of extensions of regular expressions called context-free expressions as a representation space for context-free languages. The algorithm, based on the notion of an identification in the limit, is significantly concise when compared with existing algorithms. Then, a subclass of context-free languages is examined, and a simpler algorithm for the subclass is presented. Further, a topic on meta inductive inference is briefly discussed.