No CrossRef data available.
Published online by Cambridge University Press: 20 December 2024
Let p be a prime, $q=p^n$, and
$D \subset \mathbb {F}_q^*$. A celebrated result of McConnel states that if D is a proper subgroup of
$\mathbb {F}_q^*$, and
$f:\mathbb {F}_q \to \mathbb {F}_q$ is a function such that
$(f(x)-f(y))/(x-y) \in D$ whenever
$x \neq y$, then
$f(x)$ necessarily has the form
$ax^{p^j}+b$. In this notes, we give a sufficient condition on D to obtain the same conclusion on f. In particular, we show that McConnel’s theorem extends if D has small doubling.