Remarks on context-free grammars with subregular control languages.

A context-free grammar with control language is a pair (G , R) where G is a context-free grammar and R is a regular set over the set of productions of G. Its language consists of all terminal words where the sequence of applied productions belongs to R. We study context-free grammars with control languages belonging to subsets of the set of regular languages. We prove that we can obtain only context-free languages if we use regular commutative and strictly locally 1-testable languages. By strictly locally k -testable, k ≥ 2 , ordered, union-free, ordered, and regular circular control languages, we have no loss in the generative power, i.e., we generate the same family which is obtained by arbitrary regular control sets. • Continuation of investigations the "power/simplification" of families of subregular languages. • Continuation of the work done by the author in the papers [3] , [4] , and [6]. • Research related to papers by Salomaa from the sixties and seventies. • Result on commutative control languages is interesting since it differs from the results for other regulation mechanisms. [ABSTRACT FROM AUTHOR]