Tight multiple twins in permutations

Abstract

Two permutations are similar if they have the same length and the same relative order. A collection of $r\ge 2$ disjoint, similar subsequences of a permutation $\pi$ form $r$-twins in $\pi$. We study the longest guaranteed length of $r$-twins which are tight in the sense that either each twin alone forms a block or their union does. We address the same question with respect to a random permutation.