English

New results on pseudosquare avoidance

Formal Languages and Automata Theory 2019-04-22 v1 Discrete Mathematics Combinatorics

Abstract

We start by considering binary words containing the minimum possible numbers of squares and antisquares (where an antisquare is a word of the form xxx \overline{x}), and we completely classify which possibilities can occur. We consider avoiding xp(x)x p(x), where pp is any permutation of the underlying alphabet, and xt(x)x t(x), where tt is any transformation of the underlying alphabet. Finally, we prove the existence of an infinite binary word simultaneously avoiding all occurrences of xh(x)x h(x) for every nonerasing morphism hh and all sufficiently large words xx.

Keywords

Cite

@article{arxiv.1904.09157,
  title  = {New results on pseudosquare avoidance},
  author = {Tim Ng and Pascal Ochem and Narad Rampersad and Jeffrey Shallit},
  journal= {arXiv preprint arXiv:1904.09157},
  year   = {2019}
}
R2 v1 2026-06-23T08:44:40.789Z