A problem in comparative order theory

Abstract

Write $\mathrm{ord}_p(\cdot)$ for the multiplicative order in $\mathbb{F}_p^{\times}$. Recently, Matthew Just and the second author investigated the problem of classifying pairs $α, β\in \mathbb{Q}^{\times}\setminus\{\pm 1\}$ for which $\mathrm{ord}_p(α) > \mathrm{ord}_p(β)$ holds for infinitely many primes $p$. They called such pairs order-dominant. We describe an easily-checkable sufficient condition for $α,β$ to be order-dominant. Via the large sieve, we show that almost all integer pairs $α,β$ satisfy our condition, with a power savings on the size of the exceptional set.