Semigroups and languages of dot-depth 2

  • Howard Straubing
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 226)


This paper is a contribution to the problem of effectively determining the dot-depth of a star-free language, a problem in the theory of automata and formal languages with close connections to algebra and formal logic. We conjecture an effective criterion for determining whether a given language has dot-depth 2. The condition is shown to be necessary in general, and sufficient for languages over a two-letter alphabet. The condition involves a novel use of categories in the study of semigroup-theoretic problems.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • Howard Straubing
    • 1
  1. 1.Department of Computer ScienceBoston CollegeChestnut Hill

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