English

Classifying subcategories of modules over Noetherian algebras

Representation Theory 2023-05-30 v5

Abstract

The aim of this paper is to unify classification theories of torsion classes of finite dimensional algebras and commutative Noetherian rings. For a commutative Noetherian ring RR and a module-finite RR-algebra Λ\Lambda, we study the set torsΛ\mathsf{tors} \Lambda (respectively, torfΛ\mathsf{torf}\Lambda) of torsion (respectively, torsionfree) classes of the category of finitely generated Λ\Lambda-modules. We construct a bijection from torfΛ\mathsf{torf}\Lambda to ptorf(κ(p)RΛ)\prod_{\mathfrak{p}} \mathsf{torf}(\kappa(\mathfrak{p}) \otimes_R \Lambda ), and an embedding Φt\Phi_{\rm t} from torsΛ\mathsf{tors} \Lambda to TR(Λ):=ptors(κ(p)RΛ)\mathbb{T}_R(\Lambda):=\prod_{\mathfrak{p}} \mathsf{tors}(\kappa(\mathfrak{p}) \otimes_R \Lambda), where p\mathfrak{p} runs all prime ideals of RR. When Λ=R\Lambda=R, these give classifications of torsionfree classes, torsion classes and Serre subcategories of modR\mathsf{mod} R due to Takahashi, Stanley-Wang and Gabriel. To give a description of ImΦt\mathrm{Im} \Phi_{\rm t}, we introduce the notion of compatible elements in TR(Λ)\mathbb{T}_R(\Lambda), and prove that all elements in ImΦt\mathrm{Im} \Phi_{\rm t} are compatible. We give a sufficient condition on (R,Λ)(R, \Lambda) such that all compatible elements belong to ImΦt\mathrm{Im} \Phi_{\rm t} (we call (R,Λ)(R, \Lambda) compatible in this case). For example, if RR is semi-local and dimR1\dim R \leq 1, then (R,Λ)(R, \Lambda) is compatible. We also give a sufficient condition in terms of silting Λ\Lambda-modules. As an application, for a Dynkin quiver QQ, (R,RQ)(R, RQ) is compatible and we have a poset isomorphism torsRQHomposet(SpecR,CQ)\mathsf{tors} RQ \simeq \mathrm{Hom}_{\rm poset}(\mathrm{Spec} R, \mathfrak{C}_Q) for the Cambrian lattice CQ\mathfrak{C}_Q of QQ.

Keywords

Cite

@article{arxiv.2106.00469,
  title  = {Classifying subcategories of modules over Noetherian algebras},
  author = {Osamu Iyama and Yuta Kimura},
  journal= {arXiv preprint arXiv:2106.00469},
  year   = {2023}
}

Comments

43 pages, the structure of Section 2 was modified, Subsection 3.6 was added

R2 v1 2026-06-24T02:42:29.882Z