English

A family of formulas with reversal of high avoidability index

Combinatorics 2018-02-14 v1

Abstract

We present an infinite family of formulas with reversal whose avoidability index is bounded between 4 and 5, and we show that several members of the family have avoidability index 5. This family is particularly interesting due to its size and the simple structure of its members. For each k{4,5}k\in\{4,5\}, there are several previously known avoidable formulas (without reversal) of avoidability index kk, but they are small in number and they all have rather complex structure.

Keywords

Cite

@article{arxiv.1611.03535,
  title  = {A family of formulas with reversal of high avoidability index},
  author = {James Currie and Lucas Mol and Narad Rampersad},
  journal= {arXiv preprint arXiv:1611.03535},
  year   = {2018}
}

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19 pages