On representing recursively enumerable languages by internal contextual languages

Equality sets for recursively enumerable languages

We consider shifted equality sets of the form EG(a, g1, g2) = {w | g1(w) = ag2(w)}, where g1 and g2 are nonerasing morphisms and a is a letter. We are interested in the family consisting of the languages h(EG(J)), where h is a coding and EG(J) is a shifted equality set. We prove several closure properties for this family. Moreover, we show that every every recursively enumerable language L ⊆ A∗...

Polynomial Generators of Recursively Enumerable Languages

Partial Learning of Recursively Enumerable Languages

This paper studies several typical learning criteria in the model of partial learning of r.e. sets in the recursion-theoretic framework of inductive inference. Its main contribution is a complete picture of how the criteria of confidence, consistency and conservativeness in partial learning of r.e. sets separate, also in relation to basic criteria of learning in the limit. Thus this paper const...

Characterizations of Recursively Enumerable Languages by Means of Insertion Grammars

An insertion grammar is based on pure rules of the form uu + lc~v (the string x is inserted in the context (u,u)). A strict subfamily of the context-sensitive family is obtained, incomparable with the family of linear languages. We prove here that each recursively enumerable language can be written as the weak coding of the image by an inverse morphism of a language generated by an insertion gr...

REPRESENTATIONS OF RECURSIVELY ENUMERABLE ARRAY LANGUAGES BY d-DIMENSIONAL CONTEXTUAL ARRAY GRAMMARS