Multiplicity in triangulated categories

Fuente: arXiv
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Autori principali: Bergh, Petter Andreas, Jorgensen, David A., Thompson, Peder
Natura: Preprint
Pubblicazione: 2025
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author Bergh, Petter Andreas
Jorgensen, David A.
Thompson, Peder
author_facet Bergh, Petter Andreas
Jorgensen, David A.
Thompson, Peder
contents We lay out the theory of a multiplicity in the setting of a triangulated category having a central ring action from a graded-commutative ring $R$, in other words, an $R$-linear triangulated category. The invariant we consider is modelled on those for graded modules over a commutative graded ring. We show that this invariant is determined by the leading coefficients of the Hilbert polynomials expressing the lengths of certain Hom sets. Our theory is a natural analogue of Hochster's theta invariant for homology and Buchweitz's Herbrand difference for cohomology. Moreover, we give applications to vanishing of cohomology and modules over local complete intersection rings, group algebras of a finite group, and certain finite dimensional algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2506_02437
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Multiplicity in triangulated categories
Bergh, Petter Andreas
Jorgensen, David A.
Thompson, Peder
K-Theory and Homology
Commutative Algebra
Category Theory
We lay out the theory of a multiplicity in the setting of a triangulated category having a central ring action from a graded-commutative ring $R$, in other words, an $R$-linear triangulated category. The invariant we consider is modelled on those for graded modules over a commutative graded ring. We show that this invariant is determined by the leading coefficients of the Hilbert polynomials expressing the lengths of certain Hom sets. Our theory is a natural analogue of Hochster's theta invariant for homology and Buchweitz's Herbrand difference for cohomology. Moreover, we give applications to vanishing of cohomology and modules over local complete intersection rings, group algebras of a finite group, and certain finite dimensional algebras.
title Multiplicity in triangulated categories
topic K-Theory and Homology
Commutative Algebra
Category Theory
url https://arxiv.org/abs/2506.02437