CLOSURE-PROPERTIES OF SLENDER LANGUAGES

We investigate languages, where the number of words of every length is bounded from above by a constant independent of the length. The issue s involved are very basic in the theory of formal languages and, moreo ver, have arisen in some recent studies in cryptography. This paper de als with closure properties of such ''slender'' languages with respect to a number of operations, some of them introduced very recently. Clo sure is considered both in general and with respect to slender languag es in the families of the Chomsky hierarchy.