Learnability of a subclass of extended pattern languages

Abstract

A generalization of regular pattern where each variable occurring in the pattern occurs exactly m times for some positive integer m is introduced. Such patterns are referred to as quasi-regular patterns, and for each m, the corresponding class of extended pattern languages is denoted QRPm. It is shown that for each m, the class QRPm is identifiable in the limit texts. The proof uses a sophisticated combinatorial argument for bounding the search space. It is also shown that the class of UmQRPm is identifiable in the limit from texts.