On sparseness, ambiguity and other decision problems for acceptors and transducers

  • Oscar H.Ibarra
  • B. Ravikumar
Contributed Papers
Part of the Lecture Notes in Computer Science book series (LNCS, volume 210)

Abstract

We consider some decision problems on sparseness, degrees of ambiguity and multiple valuedness concerning finite-state and pushdown acceptors and transducers. A language L is sparse if there is a polynomial P such that the number of strings of length n in L is atmost P(n). A recognizer (transducer) is of polynomial ambiguity (valued) if there exists a polynomial P such that the number of derivations (outputs) for any input of length n is at most P(n). We relate these problems and show that they are decidable for finite-state devices. For cfl's, only the sparseness problem is decidable. We also study some properties of structure generating function defined as fL(z)=Σanzn, where an is the number of strings of length n in a language L. Our results are useful in proving the non-regularity/non-context-freeness of some languages.

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Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • Oscar H.Ibarra
    • 1
  • B. Ravikumar
    • 1
  1. 1.Department of Computer ScienceUniversity of MinnesotaMinneapolis

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