Characterization of $\PSL(2,q)$ by the number of singular elements

Rulin Shen, Deyu Yan

Given a finite group $G$, let $\ddot{I}€(G)$ denote the set of all primes that divide the order of $G$. For a prime $r\in \ddot{I}€(G)$, we define $r$-singular elements as those elements of $G$…