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    Four Small Universal Turing Machines


    Neary, Turlough and Woods, Damien (2009) Four Small Universal Turing Machines. Fundamenta Informaticae, 91 (1). pp. 123-144. ISSN 0169-2968

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    Abstract

    We present universal Turing machines with state-symbol pairs of (5, 5), (6, 4), (9, 3) and (15, 2). These machines simulate our new variant of tag system, the bi-tag system and are the smallest known single-tape universal Turing machines with 5, 4, 3 and 2-symbols, respectively. Our 5-symbolmachine uses the same number of instructions (22) as the smallest known universal Turing machine by Rogozhin. Also, all of the universalmachines we present here simulate Turing machines in polynomial time.

    Item Type: Article
    Additional Information: Note that the pdf has incorrect page numbers
    Keywords: 2-tag system; Bi-tag systems; Computational complexity; Polynomial time; Post system; Small universal Turing machine;
    Academic Unit: Faculty of Science and Engineering > Computer Science
    Faculty of Science and Engineering > Research Institutes > Hamilton Institute
    Item ID: 12416
    Identification Number: https://doi.org/10.3233/FI-2009-0036
    Depositing User: Damien Woods
    Date Deposited: 14 Feb 2020 15:14
    Journal or Publication Title: Fundamenta Informaticae
    Publisher: IOS Press
    Refereed: Yes
    URI:

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