A characterization of local regular languages

Abstract

As every non-empty word is a power of a unique primitive word, a set of primitive roots of a language is like an independent subset of a vector space. A language having finitely many primitive roots is called a local language. The purpose of this paper is to characterize local regular languages. We show that whether a regular language is local or not is decidable. In the meanwhile, two characterizations of local regular languages are derived. (C) 1998 Elsevier Science B.V. All rights reserved.