Covering theory, (mono)morphism categories and stable Auslander algebras

Abstract

Let $\mathcal{A}$ be a locally bounded $k$-category and $G$ a torsion-free group of $k$-linear automorphisms of $\mathcal{A}$ acting freely on the objects of $\mathcal{A},$ and $F:\mathcal{A}\to \mathcal{B}$ is a Galois functor. We extend naturally the push-down functor $F_{\lambda }$ to the functor $\rm{H}\rm{F}_λ:\rm{H}(\rm{mod}\mbox{-} \mathcal{A})\rightarrow \rm{H}(\rm{mod}\mbox{-} \mathcal{B})$, resp. $\mathcal{S} \rm{F}_λ:\mathcal{S}(\rm{mod}\mbox{-} \mathcal{A})\rightarrow \mathcal{S}(\rm{mod}\mbox{-} \mathcal{B})$, between the corresponding morphism categories, resp. monomorphism categories, of $\rm{mod}\mbox{-} \mathcal{A}$ and $\rm{mod}\mbox{-} \mathcal{B}$. Under some additional conditions, we show that $\rm{H}(\rm{mod}\mbox{-}\mathcal{A})$, resp. $\mathcal{S}( \rm{mod}\mbox{-}\mathcal{A})$, is locally bounded if and only if $\rm{H}(\rm{mod}\mbox{-} \mathcal{B})$, resp. $\mathcal{S}(\rm{mod}\mbox{-}\mathcal{B})$, is of finite representation type. As an application, we show that the stable Auslander algebra of a representation-finite selfinjective algebra $\Lambda$ is again representation-finite if and only if $\Lambda$ is of Dynkin type ${\mathbb{A}}_n$ with $n⩽4$.

A few errors have been fixed. The paper is dedicated to the memory of Professor Andrzej Skowronski