A string w is said to be a minimal unique substring (MUS) of a string T if w occurs exactly once in T, and any proper substring of w occurs at least twice in T. It is known that the number of MUSs in a string T of length n is at most n, and that the set MUS(T) of all MUSs in T can be computed in O(n) time [Ilie and Smyth, 2011]. Let MUS(T,i) denote the set of MUSs that contain a position i in a string T. In this short paper, we present matching Θ(n) upper and lower bounds for the number ∣MUS(T,i)∣ of MUSs containing a position i in a string T of length n.
@article{arxiv.2508.16092,
title = {On the number of MUSs crossing a position},
author = {Hiroto Fujimaru and Takuya Mieno and Shunsuke Inenaga},
journal= {arXiv preprint arXiv:2508.16092},
year = {2025}
}