2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/157739In this paper we show that the following problem is NP-complete: Given an alphabet $Σ$ and two strings over $Σ$, the question is whether there exists a permutation of $Σ$ which is a subsequence of both of the given strings.Computational Complexitytext