Palindromes patterns
By Srecko Brlek
Also appears in collection : New advances in symbolic dynamics / Dynamique symbolique, Combinatoire des mots. Calculabilité. Automates
The study of palindromes and their generalizations in a word has gained a lot of interest in the last 20 years, motivated by applications in physics, biology, discrete geometry, to name only a few. Using Sebastien Ferenczi as an example, we illustrate the computation of its palindromic complexity and its relation with the usual factor complexity, via an identity attributed to Brlek and Reutenauer involving also the palindromic defect. Periodic infinite words as well as the family of words with language closed by reversal also satisfy the identity. The identity remains valid when palindromic is replaced by $\sigma$-palindromic, and we also discuss some other patterns.
