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This paper shows a new phenomenon in higher cluster tilting theory. For each positive integer d, we exhibit a triangulated category C with the following properties. On the one hand, the d-cluster tilting subcategories of C have very simple…

Representation Theory · Mathematics 2015-04-22 Thorsten Holm , Peter Jorgensen

Let $\mathcal{A}$ be an abelian length category containing a $d$-cluster tilting subcategory $\mathcal{M}$. We prove that a subcategory of $\mathcal{M}$ is a $d$-torsion class if and only if it is closed under $d$-extensions and…

Representation Theory · Mathematics 2025-02-12 Jenny August , Johanne Haugland , Karin M. Jacobsen , Sondre Kvamme , Yann Palu , Hipolito Treffinger

For an exact category $\mathcal{E}$ with enough projectives and with a $d\mathbb{Z}$-cluster tilting subcategory, we show that the singularity category of $\mathcal{E}$ admits a $d\mathbb{Z}$-cluster tilting subcategory. To do this we…

Representation Theory · Mathematics 2021-08-09 Sondre Kvamme

We introduce the notion of an $n$-exact dg-category. This notion provides a higher analogue of Chen's exact dg-category, in the sense that the case where $n$ equals 1 recovers exact dg-categories. We prove that, under a suitable vanishing…

Category Theory · Mathematics 2026-04-08 Nao Mochizuki , Hiroyuki Nakaoka

We study the cluster combinatorics of $d-$cluster tilting objects in $d-$cluster categories. By using mutations of maximal rigid objects in $d-$cluster categories which are defined similarly for $d-$cluster tilting objects, we prove the…

Representation Theory · Mathematics 2009-02-14 Yu Zhou , Bin Zhu

Let D be a triangulated category with a cluster tilting subcategory U. The quotient category D/U is abelian; suppose that it has finite global dimension. We show that projection from D to D/U sends cluster tilting subcategories of D to…

Representation Theory · Mathematics 2008-10-03 Thorsten Holm , Peter Jorgensen

In this paper, we study ideal quotients of triangulated categories by higher cluster tilting subcategories. Koenig and Zhu proved that the ideal quotient by a $2$-cluster tilting subcategory is an abelian category; moreover, by Morita's…

Representation Theory · Mathematics 2026-05-26 Nao Mochizuki

We introduce the concept of a pseudo-cluster tilting subcategory from the viewpoint of the fact that the quotient of an exact category by a cluster tilting subcategory is an abelian category. We prove that the quotients in the case of…

Representation Theory · Mathematics 2023-03-14 Jie Xu , Yuefei Zheng

Building on work of Jasso, we prove that any projectively generated $d$-abelian category is equivalent to a $d$-cluster tilting subcategory of an abelian category with enough projectives. This supports the claim that $d$-abelian categories…

Category Theory · Mathematics 2016-10-25 Sondre Kvamme

Let $\mathcal C$ be a Krull-Schmidt triangulated category with shift functor $[1]$ and $\mathcal R$ be a rigid subcategory of $\mathcal C$. We are concerned with the mutation of two-term weak $\mathcal R[1]$-cluster tilting subcategories.…

Representation Theory · Mathematics 2024-08-29 Yu Liu , Jixing Pan , Panyue Zhou

In this note, we consider the $d$-cluster-tilted algebras, the endomorphism algebras of $d$-cluster-tilting objects in $d$-cluster categories. We show that a tilting module over such an algebra lifts to a $d$-cluster-tilting object in this…

Representation Theory · Mathematics 2008-12-29 Pin Liu

In this paper we introduce $n\mathbb{Z}$-abelian and $n\mathbb{Z}$-exact categories by axiomatising properties of $n\mathbb{Z}$-cluster tilting subcategories. We study this categories and show that every $n\mathbb{Z}$-cluster tilting…

Category Theory · Mathematics 2022-02-15 Ramin Ebrahimi , Alireza Nasr-Isfahani

A subcategory of an abelian category is wide if it is closed under sums, summands, kernels, cokernels, and extensions. Wide subcategories provide a significant interface between representation theory and combinatorics. If $\Phi$ is a finite…

Representation Theory · Mathematics 2019-11-22 Martin Herschend , Peter Jorgensen , Laertis Vaso

Let $\mathscr{C}$ be a 2-Calabi-Yau triangulated category, and let $\mathscr{T}$ be a cluster tilting subcategory of $\mathscr{C}$. An important result from Dehy and Keller tells us that a rigid object $c \in \mathscr{C}$ is uniquely…

Representation Theory · Mathematics 2019-08-30 Joseph Reid

We study the maximal rigid subcategories in $2-$CY triangulated categories and their endomorphism algebras. Cluster tilting subcategories are obviously maximal rigid; we prove that the converse is true if the $2-$CY triangulated categories…

Representation Theory · Mathematics 2015-03-17 Yu Zhou , Bin Zhu

Let $A$ be a finite-dimensional algebra, and $\mathfrak{M}$ be a $d$-cluster tilting subcategory of mod$A$. From the viewpoint of higher homological algebra, a natural question to ask is when $\mathfrak{M}$ induces a $d$-cluster tilting…

Representation Theory · Mathematics 2023-08-29 Ramin Ebrahimi , Alireza Nasr-Isfahani

Building on previous work, we study the splitting of idempotents in the category of extensions $\mathbb{E}\operatorname{-Ext}(\mathcal{C})$ associated to a pair $(\mathcal{C},\mathbb{E})$ of an additive category and a biadditive functor to…

Category Theory · Mathematics 2023-10-27 Raphael Bennett-Tennenhaus , Johanne Haugland , Mads Hustad Sandøy , Amit Shah

Starting from its original definition in module categories with respect to projective modules, the index has played an important role in various aspects of homological algebra, categorification of cluster algebras and $K$-theory. In the…

Representation Theory · Mathematics 2025-09-22 Francesca Fedele , Peter Jørgensen , Amit Shah

Cluster algebras are categorified by cluster categories, and $g$-vectors are categorified by the classic index with respect to cluster tilting subcategories. However, the recently introduced completed discrete cluster categories of Dynkin…

Representation Theory · Mathematics 2024-12-17 Francesca Fedele , Peter Jorgensen , Amit Shah

We investigate the role of gentle algebras in higher homological algebra. In the first part of the paper, we show that if the module category of a gentle algebra $\Lambda$ contains a $d$-cluster tilting subcategory for some $d \geq 2$, then…

Representation Theory · Mathematics 2022-05-02 Johanne Haugland , Karin M. Jacobsen , Sibylle Schroll
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