On images of subshifts under injective morphisms of symbolic varieties

Abstract

We show that the image of a subshift $X$ under various injective morphisms of symbolic algebraic varieties over monoid universes with algebraic variety alphabets is a subshift of finite type, resp. a sofic subshift, if and only if so is $X$. Similarly, let $G$ be a countable monoid and let $A$, $B$ be Artinian modules over a ring. We prove that for every closed subshift submodule $\Sigma \subset A^G$ and every injective $G$-equivariant uniformly continuous module homomorphism $\tau \colon \Sigma \to B^G$, a subshift $\Delta \subset \Sigma$ is of finite type, resp. sofic, if and only if so is the image $\tau(\Delta)$. Generalizations for admissible group cellular automata over admissible Artinian group structure alphabets are also obtained.