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How to Synchronize the Heads of a Multitape Automaton

  • Oscar H. Ibarra
  • Nicholas Q. Tran
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7381)

Abstract

Given an n-tape automaton M with a one-way read-only head per tape and a right end marker $ on each tape, we say that M is aligned or 0-synchronized (or simply, synchronized) if for every n-tuple x = (x 1, …, x n ) that is accepted, there is a computation on x such that at any time during the computation, all heads, except those that have reached the end marker, are on the same position. When a head reaches the marker, it can no longer move. As usual, an n-tuple x = (x 1, …, x n ) is accepted if M eventually reaches the configuration where all n heads are on $ in an accepting state. In two recent papers, we looked at the problem of deciding, given an n-tape automaton of a given type, whether there exists an equivalent synchronized n-tape automaton of the same type. In this paper, we exhibit various classes of multitape automata which can(not) be converted to equivalent synchronized multitape automata.

Keywords

multitape automata aligned synchronized semilinear decidable undecidable 1-reversal counters reversal-bounded counters 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Oscar H. Ibarra
    • 1
  • Nicholas Q. Tran
    • 2
  1. 1.Department of Computer ScienceUniversity of CaliforniaSanta BarbaraUSA
  2. 2.Department of Mathematics & Computer ScienceSanta Clara UniversitySanta ClaraUSA

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