Frobenius Categories over a Triangular Matrix Ring and Comma Categories

Abstract

We introduce the dual notions of $\mathcal{E}(\mathcal{X},M,\mathcal{Y})$ and $\mathcal{M}(\mathcal{X},M,\mathcal{Y})$, and investigate when they have enough injective objects or projective objects, when they are resolving or co-resolving, and when they are Frobenius categories. In the case that they are Frobenius categories, we establish a recollement of their stable categories. Finally some applications to comma categories are given.

20 pages to appear in Comm. Algebra