Remarks on generalized Post Correspondence Problem

  • T. Harju
  • J. Karhumäki
  • D. Krob
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1046)


It is shown that Post Correspondence Problem remains undecidable even in the case where one of the morphisms is fixed. Accordingly the generalized PCP is undecidable even in the case where both of the morphisms are fixed, and, moreover, the cardinality of their domain alphabet is 7. In particular, GPCP(7) is undecidable. On the other hand, GPCP(2) is not only decidable, but, as we show here, its all solutions can be effectively found.


Word Problem Solvability Condition Finite Automaton Binary Case Bounded Delay 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • T. Harju
    • 1
  • J. Karhumäki
    • 1
  • D. Krob
    • 2
  1. 1.Department of MathematicsUniversity of TurkuTurkuFinland
  2. 2.Institute Blaise Pascal (LITP), CNRSUniversite Paris VIIParisFrance

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