Small Weakly Universal Turing Machines

  • Turlough Neary
  • Damien Woods
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5699)


We give small universal Turing machines with state-symbol pairs of (6,2), (3,3) and (2,4). These machines are weakly universal, which means that they have an infinitely repeated word to the left of their input and another to the right. They simulate Rule 110 and are currently the smallest known weakly universal Turing machines. Despite their small size these machines are efficient polynomial time simulators of Turing machines.


Turing Machine Universal Machine Universal Turing Machine Tape Head Elementary Cellular Automaton 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Turlough Neary
    • 1
  • Damien Woods
    • 2
  1. 1.Boole Centre for Research in InformaticsUniversity College CorkIreland
  2. 2.Department of Computer Science and Artificial IntelligenceUniversity of SevilleSpain

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