Some undecidability results for weakly confluent monadic string-rewriting systems

  • Friedrich Otto
Submitted Contributions
Part of the Lecture Notes in Computer Science book series (LNCS, volume 539)


For a finite weakly confluent monadic string-rewriting system R presenting a group the set of valid linear sentences is decidable. Thus, many decision problems for R can be solved in a uniform way. Here we show that this is no longer true in general if R is a finite weakly confluent monadic string-rewriting system that does not present a group. In fact, we construct a system R of this form that has an undecidable word problem. Some additional undecidability results as well as some decidability results for finite weakly confluent monadic string-rewriting systems are also presented.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • Friedrich Otto
    • 1
  1. 1.Fachbereich Mathematik/InformatikGesamthochschule Kassel — UniversitätKasselWest Germany

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