English

$d$-Auslander-Reiten sequences in subcategories

Representation Theory 2020-04-16 v2

Abstract

Let Φ\Phi be a finite dimensional algebra over a field kk. Kleiner described the Auslander-Reiten sequences in a precovering extension closed subcategory X\mathcal{X}\subseteq mod Φ\Phi. If XXX\in\mathcal{X} is an indecomposable such that ExtΦ1(X,X)0_{\Phi}^1(X,\mathcal{X})\neq 0 and ζX\zeta X is the unique indecomposable direct summand of the X\mathcal{X}-cover g:YDg:Y\rightarrow DTrXX such that ExtΦ1(X,ζX)0_{\Phi}^1(X,\zeta X)\neq 0, then there is an Auslander-Reiten sequence in X\mathcal{X} of the form \begin{align*} \epsilon: 0\rightarrow \zeta X\rightarrow X'\rightarrow X\rightarrow 0. \end{align*} Moreover, when EndΦ(X)_\Phi (X) modulo the morphisms factoring through a projective is a division ring, Kleiner proved that each non-split short exact sequence of the form \begin{align*} \delta: 0\rightarrow Y\rightarrow Y'\xrightarrow{\eta} X\rightarrow 0 \end{align*} is such that η\eta is right almost split in X\mathcal{X}, and the pushout of δ\delta along gg gives an Auslander-Reiten sequence in mod Φ\Phi ending at XX. In this paper, we give higher dimensional generalisations of this. Let d1d\geq 1 be an integer. A dd-cluster tilting subcategory F\mathcal{F}\subseteq mod Φ\Phi plays the role of a higher mod Φ\Phi. Such an F\mathcal{F} is a dd-abelian category, where kernels and cokernels are replaced by complexes of dd objects and short exact sequences by complexes of d+2d+2 objects. We give higher versions of the above results for an additive "dd-extension closed" subcategory X\mathcal{X} of F\mathcal{F}.

Keywords

Cite

@article{arxiv.1808.02709,
  title  = {$d$-Auslander-Reiten sequences in subcategories},
  author = {Francesca Fedele},
  journal= {arXiv preprint arXiv:1808.02709},
  year   = {2020}
}

Comments

27 pages. Final version, which has been accepted for publication in the Proceedings of the Edinburgh Mathematical Society

R2 v1 2026-06-23T03:27:42.940Z