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A reasonably-sized morphism giving Abelian critical exponent less than 2

By James D. Currie

Appears in collection : Combinatorics on words / Combinatoire des mots - Week 5

It is known that there are infinite words over finite alphabets with Abelian repetition threshold arbitrarily close to 1; however, the construction previously used involves huge alphabets. In this note we give a short cyclic morphism (length 13) over an 8-letter alphabet yielding an Abelian repetition threshold less than 1.8.

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Citation data

  • DOI 10.24350/CIRM.V.20147903
  • Cite this video Currie, James D. (26/02/2024). A reasonably-sized morphism giving Abelian critical exponent less than 2. CIRM. Audiovisual resource. DOI: 10.24350/CIRM.V.20147903
  • URL https://dx.doi.org/10.24350/CIRM.V.20147903

Bibliography

  • CURRIE, James D. et RAMPERSAD, Narad. A small morphism giving Abelian repetition threshold less than 2. arXiv preprint arXiv:2312.16665, 2023. - https://doi.org/10.48550/arXiv.2312.16665
  • CASSAIGNE, Julien et CURRIE, James D. Words strongly avoiding fractional powers. European Journal of Combinatorics, 1999, vol. 20, no 8, p. 725-737. - https://doi.org/10.1006/eujc.1999.0329
  • CURRIE, James D. What Is the Abelian Analogue of Dejean's Conjecture? ¹. Grammars and Automata for String Processing: From Mathematics and Computer Science to Biology, and Back, 2004, vol. 9, no Y6, p. 237.
  • CURRIE, James D. Pattern avoidance: themes and variations. Theoretical Computer Science, 2005, vol. 339, no 1, p. 7-18. - https://doi.org/10.1016/j.tcs.2005.01.004
  • CURRIE, James et RAMPERSAD, Narad. A proof of Dejean's conjecture. Mathematics of computation, 2011, vol. 80, no 274, p. 1063-1070. - http://dx.doi.org/10.1090/S0025-5718-2010-02407-X
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  • PETROVA, Elena A. et SHUR, Arseny M. Abelian repetition threshold revisited. In : International Computer Science Symposium in Russia. Cham : Springer International Publishing, 2022. p. 302-319. - http://dx.doi.org/10.1007/978-3-031-09574-0_19
  • RAO, Michaël. Last cases of Dejean's conjecture. Theoretical Computer Science, 2011, vol. 412, no 27, p. 3010-3018. - https://doi.org/10.1016/j.tcs.2010.06.020
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