$\ddot{I}„$-cluster morphism categories of factor algebras

Abstract

We take a novel lattice-theoretic approach to the $\ddot{I}„$-cluster morphism category $\mathfrak{T}(A)$ of a finite-dimensional algebra $A$ and define the category via the lattice of torsion classes $\mathrm{tors}A$. Using the lattice congruence induced by an ideal $I$ of $A$ we establish a functor $F_I:\mathfrak{T}(A)\to \mathfrak{T}(A/I)$. If $\mathrm{tors}A$ is finite, $F_I$ is a regular epimorphism in the category of small categories and we characterise when $F_I$ is full and faithful. The construction is purely combinatorial, meaning that the lattice of torsion classes determines the $\ddot{I}„$-cluster morphism category up to equivalence.

25 pages, comments welcome; v2: added results about $F_I$ to Section 6, removed results about the inclusion functor