The p-width of the alternating groups

Abstract

Let $p$ be a fixed prime. For a finite group generated by elements of order $p$, the $p$-width is defined to be the minimal $k\in \mathbb{N}$ such that any group element can be written as a product of at most $k$ elements of order $p$. Let $A_n$ denote the alternating group of even permutations on $n$ letters. We show that the $p$-width of $A_n$ $(n\ge p)$ is at most $3$. This result is sharp, as there are families of alternating groups with $p$-width precisely 3, for each prime $p$.

Added Appendix concerning the work of Dvir85 that can be used to simplify the proof of our main theorem