INNER PALINDROMIC CLOSURE

Abstract

We introduce the inner palindromic closure as a new operation ♠, which consists in expanding a factor u to the left or right by a non-empty word v such that vu or uv, respectively, is a palindrome of minimal length. We investigate several language theoretic properties of the iterated inner palindromic closure ♠ (w) = U i≥0 ♠ i (w) of a word w.