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Given a finite cocommutative Hopf algebra $A$ over a commutative regular ring $R$, the lattice of localising tensor ideals of the stable category of Gorenstein projective $A$-modules is described in terms of the corresponding lattices for…

Representation Theory · Mathematics 2022-06-14 Dave Benson , Srikanth B. Iyengar , Henning Krause , Julia Pevtsova

We prove that the category of commutative Hopf algebras over a field $k$ is co-semi-abelian. Consequently, the category of affine group $k$-schemes is semi-abelian. We establish coregularity by identifying the orthogonal factorization…

Category Theory · Mathematics 2026-02-25 David Forsman

In this paper we develop an axiomatic setup for algorithmic homological algebra of Abelian categories. This is done by exhibiting all existential quantifiers entering the definition of an Abelian category, which for the sake of…

Commutative Algebra · Mathematics 2017-10-27 Mohamed Barakat , Markus Lange-Hegermann

We initiate a program aimed at classifying thick ideals, Balmer spectra, and submodule categories of various stable categories of bimodules and modules for finite dimensional selfinjective algebras, and at clarifying the relationship…

Category Theory · Mathematics 2026-01-12 Øyvind Solberg , Kent B. Vashaw , Sarah Witherspoon

We develop a theory of perfect algebraic stacks that extend our theory of perfect algebraic spaces in arXiv:2303.07672, arXiv:2303.08502 to the setting of algebraic stacks. We prove several desired properties of perfect algebraic stacks.…

Algebraic Geometry · Mathematics 2023-03-20 Tianwei Liang

We investigate the homogeneity of certain kind of slices of the complete complexification of a proper complex equifocal submanifold in a symmetric space of non-compact type.

Differential Geometry · Mathematics 2010-05-27 Naoyuki Koike

For N=5, 6 and 7, using the classification of perfect quadratic forms, we compute the homology of the Voronoi cell complexes attached to the modular groups SL_N(\Z) and GL_N(\Z). From this we deduce the rational cohomology of those groups.

Number Theory · Mathematics 2010-01-07 Philippe Elbaz-Vincent , Herbert Gangl , Christophe Soulé

We classify fully commutative elements in the affine Coxeter group of type $\tilde{A_{n}}$. We give a normal form for such elements, then we propose an application of this normal form: we lift these fully commutative elements to the affine…

Group Theory · Mathematics 2013-11-28 Sadek Al Harbat

In the paper we describe the almost split sequences in the homotopy category of perfect complexes over a gentle algebra.

Representation Theory · Mathematics 2009-03-31 Grzegorz Bobinski

We compute the Balmer spectrum of a certain tensor triangulated category of comodules over the mod 2 dual Steenrod algebra. This computation effectively classifies the thick subcategories, resolving a conjecture of Palmieri.

Algebraic Topology · Mathematics 2024-09-18 Collin Litterell

This paper is a summary of author's results on finite flat commutative group schemes. The properties of the generic fibre functor are discussed. A complete classification of finite local flat commutative group schemes over mixed…

Number Theory · Mathematics 2014-06-17 M. V. Bondarko

We reformulate the problem of bounding the total rank of the homology of perfect chain complexes over the group ring $\mathbb{F}_p[G]$ of an elementary abelian $p$-group $G$ in terms of commutative algebra. This extends results of Carlsson…

Algebraic Topology · Mathematics 2022-02-09 Jeremiah Heller , Marc Stephan

We connect the homotopy type of simplicial moduli spaces of algebraic structures to the cohomology of their deformation complexes. Then we prove that under several assumptions, mapping spaces of algebras over a monad in an appropriate…

Algebraic Topology · Mathematics 2015-07-20 Sinan Yalin

A global representation is a compatible collection of representations of the outer automorphism groups of the finite groups belonging to a family $\mathscr{U}$. These arise in classical representation theory, in the study of representation…

Representation Theory · Mathematics 2025-06-27 Miguel Barrero , Tobias Barthel , Luca Pol , Neil Strickland , Jordan Williamson

We investigate Hopf algebroids in the category of $L$-complete modules over a commutative Noetherian regular complete local ring. The main examples are provided by the Hopf algebroids associated to Lubin-Tate spectra in the K(n)-local…

Algebraic Topology · Mathematics 2009-06-10 Andrew Baker

We study algebraicity and smoothness of fixed point stacks for flat group schemes which have a finite composition series whose factors are either reductive or proper, flat, finitely presented, acting on algebraic stacks with affine,…

Algebraic Geometry · Mathematics 2022-09-19 Matthieu Romagny

The objective of this paper is to introduce and study completions and local homology of comodules over Hopf algebroids, extending previous work of Greenlees and May in the discrete case. In particular, we relate module-theoretic to…

Algebraic Topology · Mathematics 2019-01-18 Tobias Barthel , Drew Heard , Gabriel Valenzuela

We prove various finiteness and representability results for cohomology of finite flat abelian group schemes. In particular, we show that if $f\colon X\rightarrow \mathrm{Spec}(k)$ is a projective scheme over a field $k$ and $G$ is a finite…

Algebraic Geometry · Mathematics 2025-04-10 Daniel Bragg , Martin Olsson

We study the spectrum of prime ideals in the tensor-triangulated category of compact equivariant spectra over a finite group. We completely describe this spectrum as a set for all finite groups. We also make significant progress in…

Algebraic Topology · Mathematics 2017-03-16 Paul Balmer , Beren Sanders

We classify thick tensor ideals of finite objects in the category of rational torus-equivariant spectra, showing that they are completely determined by geometric isotropy. This is essentially equivalent to showing that the Balmer spectrum…

Algebraic Topology · Mathematics 2016-12-07 J. P. C. Greenlees