New time hierarchy results for deterministic TMS

  • Krzysztof Loryś
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 577)


We show a method of maintaining a distributed counter by 2-dimensional deterministic Turing machines with at least two tapes. Our method yields a tight time hierarchy for these machines solving an open problem posed by M. Fürer ([Fü1],[Fü2]). Moreover, we improve the best known time hierarchy theorem for one-tape off-line deterministic TMs; among others we show that this hierarchy is tight for functions bounded by polynomials.


Turing Machine Simulated Step Input Word Input Tape Universal Machine 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • Krzysztof Loryś
    • 1
  1. 1.Institute of Computer ScienceUniversity of WroclawWroclawPoland

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