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A Formalisation of the Myhill-Nerode Theorem Based on Regular Expressions

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Abstract

There are numerous textbooks on regular languages. Many of them focus on finite automata for proving properties. Unfortunately, automata are not so straightforward to formalise in theorem provers. The reason is that natural representations for automata are graphs, matrices or functions, none of which are inductive datatypes. Regular expressions can be defined straightforwardly as a datatype and a corresponding reasoning infrastructure comes for free in theorem provers. We show in this paper that a central result from formal language theory—the Myhill-Nerode Theorem—can be recreated using only regular expressions. From this theorem many closure properties of regular languages follow.

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Authors and Affiliations

  1. PLA University of Science and Technology Nanjing, Nanjing, China

    Chunhan Wu & Xingyuan Zhang

  2. King’s College London, London, UK

    Chunhan Wu & Christian Urban

Authors
  1. Chunhan Wu
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  2. Xingyuan Zhang
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  3. Christian Urban
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Corresponding author

Correspondence to Christian Urban.

Additional information

This paper is a revised and much expanded version of Wu et al. [32].

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Wu, C., Zhang, X. & Urban, C. A Formalisation of the Myhill-Nerode Theorem Based on Regular Expressions. J Autom Reasoning 52, 451–480 (2014). https://doi.org/10.1007/s10817-013-9297-2

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  • DOI: https://doi.org/10.1007/s10817-013-9297-2

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