On Test Sets for Checking Morphism Equivalence on Languages with Fair Distribution of Letters
Abstract A test set for a language L is a finite subset T of L with the property that each pair of morphisms that agrees on T also agrees on L . Some results concerning test sets for languages with fair distribution of letters are presented. The first result is that every D0L language with fair distribution of letters has a test set. The second result shows that every language L with fair distribution has a test set relative to morphisms g , h which have bounded balance on L . These results are generalizations of results of Culik II and Karhumaki (1983).