  Let $X$ be a compact metrizable group and $\Gamma$ a countable group acting
on $X$ by continuous group automorphisms. We give sufficient conditions under
which the dynamical system $(X,\Gamma)$ is surjunctive, i.e., every injective
continuous map $\tau \colon X \to X$ commuting with the action of $\Gamma$ is
surjective.
