On slender context-free languages

  • Danny Raz
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 900)


In this paper we study slender context-free languages, i.e., those containing at most a constant number of words of each length. Recently, Ilie proved that every such language can be described by a finite union of terms of the form uv i wx i y [I]. We provide a completely different proof of this, using constructive methods. This enables us to prove that thinness and slenderness are decidable. Our proofs are based upon a novel characterization of languages in terms of the structure of the infinite paths in their prefix closure. This characterization seems to be interesting in itself, and can be expanded to more general families of languages.

Key words

formal languages context-free grammars decidability 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • Danny Raz
    • 1
  1. 1.The Weizmann Institute of ScienceRehovotIsrael

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