Hotz-isomorphism theorems in formal language theory

  • Volker Diekert
  • Axel Möbus
Contributed Papers Formal Languages
Part of the Lecture Notes in Computer Science book series (LNCS, volume 294)


A language \(L \subseteq X*\)is called a language with a Hotz-isomorphism if there is a generating grammar such that its Hotz group is canonically isomorphic to F(X)/L. The main result of the paper states that L is a language with a Hotz-isomorphism if and only if F(X)/L is a finitely presentable group. We also prove an analogous result for Hotz-monoids. Further, we show when the construction of a grammar which allows the Hotz-isomorphism is effective; and we prove various undecidability results concerning this construction.


Homomorphic Image Computable Function Surjective Homomorphism Formal Language Theory Monoid Homomorphism 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • Volker Diekert
    • 1
  • Axel Möbus
    • 2
  1. 1.Institut für Informatik der Technischen Universität MünchenMünchen 2
  2. 2.Mathematisches Institut der Universität DüsseldorfDüsseldorf

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