An Exponential Gap Between LasVegas and Deterministic Sweeping Finite Automata

  • Christos Kapoutsis
  • Richard Královič
  • Tobias Mömke
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4665)


A two-way finite automaton is sweeping if its input head can change direction only on the end-markers. For each n ≥ 2, we exhibit a problem that can be solved by a O(n 2)-state sweeping LasVegas automaton, but needs 2Ω(n) states on every sweeping deterministic automaton.


Turing Machine Input String Rightmost Column Tree Order Leftmost Column 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Christos Kapoutsis
    • 1
  • Richard Královič
    • 1
  • Tobias Mömke
    • 1
  1. 1.Department of Computer Science, ETH Zürich 

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