Published online by Cambridge University Press: 27 November 2015
This paper considers the general question of when a topological action of a countable group can be factored into a direct product of non-trivial actions. In the early 1980s, D. Lind considered such questions for $\mathbb{Z}$-shifts of finite type. In particular, we study direct factorizations of subshifts of finite type over
$\mathbb{Z}^{d}$ and other groups, and
$\mathbb{Z}$-subshifts which are not of finite type. The main results concern direct factors of the multidimensional full
$n$-shift, the multidimensional
$3$-colored chessboard and the Dyck shift over a prime alphabet. A direct factorization of an expansive
$\mathbb{G}$-action must be finite, but an example is provided of a non-expansive
$\mathbb{Z}$-action for which there is no finite direct-prime factorization. The question about existence of direct-prime factorization of expansive actions remains open, even for
$\mathbb{G}=\mathbb{Z}$.