Perfectly Clustering Words and Iterated Palindromes over a Ternary Alphabet

Abstract

Recently, a new characterization of Lyndon words that are also perfectly clustering was proposed by Lapointe and Reutenauer (2024). A word over a ternary alphabet {a,b,c} is called perfectly clustering Lyndon if and only if it is the product of two palindromes and it can be written as apbqc where p and q are palindromes. We study the properties of palindromes appearing as factors p and q and their links with iterated palindromes over a ternary alphabet.