On star-free events
Yechezkel Zalcstein · 1970
It is an open problem, suggested by Papert and McNaughton, to find a decision procedure for determining whether a regular event is locally testable. In this paper we provide a partial solution, giving two effectively decidable conditions, one necessary and one sufficient, for local testability. Our proofs are for the most part algebraic, using machine decompositions and semigroup theory.