The number of composition factors of order $p$ in completely reducible groups of characteristic $p$

TL;DR

This paper establishes an upper bound on the number of prime order $p$ composition factors in completely reducible groups over finite fields, providing sharp bounds with explicit examples.

Contribution

It introduces a new bound on the number of prime $p$-order composition factors in completely reducible groups of characteristic $p$, with sharpness demonstrated through examples.

Findings

Bound on composition factors of order $p$ in terms of $d$ and $q$

The function $ ext{varepsilon}_q$ satisfies $1 \\leq \\varepsilon_q \\leq 3/2$

Examples show the bound is sharp infinitely often

Abstract

Let $q$ be a power of a prime $p$ and let $G$ be a completely reducible subgroup of $\mathrm{GL}(d,q)$. We prove that the number of composition factors of $G$ that have prime order $p$ is at most $(\varepsilon_q d-1)/(p-1)$, where $\varepsilon_q$ is a function of $q$ satisfying $1\leqslant\varepsilon_q\leqslant 3/2$. For every $q$, we give examples showing this bound is sharp infinitely often.