Decidable and Undecidable Problems of Primitive Words, Regular and Context-Free Languages

Sándor Horváth (Department of Computer Science, L. Eötvös University, Hungary)

Masami Ito (Faculty of Science, Kyoto Sangyo University, Japan)

Abstract:

For any language L over an alphabet X, we define the root set, root(L) and the degree set, deg(L) as follows: (1) root(L) = where Q is the set of all primitive words over X, (2) deg(L) = . We deal with various decidability problems related to root and degree sets.

Keywords: context-free languages, decidability problems, degree sets, regular languages, root sets