Two-Way Automata and One-Tape Machines

Read Only Versus Linear Time
  • Bruno Guillon
  • Giovanni Pighizzini
  • Luca PrigionieroEmail author
  • Daniel Průša
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11088)


It is well-known that one-tape Turing machines working in linear time are no more powerful than finite automata, namely they recognize exactly the class of regular languages. We study the costs, in terms of description sizes, of the conversion of nondeterministic finite automata into equivalent linear-time one-tape deterministic machines. We prove a polynomial blowup from two-way nondeterministic finite automata into equivalent weight-reducing one-tape deterministic machines that work in linear time. The blowup remains polynomial if the tape in the resulting machines is restricted to the portion which initially contains the input. However, in this case the machines resulting from our construction are not weight reducing, unless the input alphabet is unary.


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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Bruno Guillon
    • 1
  • Giovanni Pighizzini
    • 1
  • Luca Prigioniero
    • 1
    Email author
  • Daniel Průša
    • 2
  1. 1.Dipartimento di InformaticaUniversità degli Studi di MilanoMilanItaly
  2. 2.Faculty of Electrical EngineeringCzech Technical UniversityPragueCzech Republic

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