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Under some technical assumptions, and building on joint work with Bezrukavnikov, we prove a multiplicity formula for indecomposable tilting perverse sheaves on affine flag varieties, with coefficients in a field of characteristic $p$, in…

Representation Theory · Mathematics 2025-09-16 Simon Riche

In this paper we construct an abelian category of "mixed perverse sheaves" attached to any realization of a Coxeter group, in terms of the associated Elias-Williamson diagrammatic category. This construction extends previous work of the…

Representation Theory · Mathematics 2018-07-19 Pramod N. Achar , Simon Riche , Cristian Vay

We define admissible and weakly admissible subcategories in exact categories and prove that the former induce semi-orthogonal decompositions on the derived categories. We develop the theory of thin exact categories, an exact-category…

Representation Theory · Mathematics 2024-06-25 Agnieszka Bodzenta , Alexey Bondal

This paper is devoted to the study of the gluing construction for perverse sheaves on $G/U$ introduced by Kazhdan and Laumon ($G$ is a semisimple gourp, $U$ is the unipotent radical of a Borel subgroup in $G$). Kazhdan and Laumon…

Algebraic Geometry · Mathematics 2009-03-10 Roman Bezrukavnikov , Alexander Polishchuk

We introduce irregular constructible sheaves, which are $\mathbb{C}$-constructible with coefficients in a finite version of Novikov ring $\Lambda$ and special gradings. We show that the bounded derived category of cohomologically irregular…

Complex Variables · Mathematics 2021-07-01 Tatsuki Kuwagaki

Given a compact stratified pseudomanifold with a Thom-Mather stratification and a class of riemannian metrics over its regular part, we study the relationships between the $L^{2}$ de Rham and Hodge cohomology and the intersection cohomology…

Differential Geometry · Mathematics 2012-06-07 Francesco Bei

We give a geometric model for the category of coherent sheaves over the weighted projective line of type $(p,q)$ in terms of an annulus with marked points on its boundary. We establish a bijection between indecomposable sheaves over the…

Representation Theory · Mathematics 2023-10-10 Jianmin Chen , Shiquan Ruan , Hongxia Zhang

Several important cases of vector bundles with extra structure (such as Higgs bundles and triples) may be regarded as examples of twisted representations of a finite quiver in the category of sheaves of modules on a variety/manifold/ringed…

Algebraic Geometry · Mathematics 2007-05-23 Peter B. Gothen , Alastair D. King

We define and study a relative perverse $t$-structure associated with any finitely presented morphism of schemes $f: X\to S$, with relative perversity equivalent to perversity of the restrictions to all geometric fibres of $f$. The…

Algebraic Geometry · Mathematics 2023-05-11 David Hansen , Peter Scholze

Using the new approach to analytic geometry developed by Clausen and Scholze by means of condensed mathematics, we prove that for every affinoid analytic adic space $X$, pseudocoherent complexes, perfect complexes, and finite projective…

Algebraic Geometry · Mathematics 2021-11-16 Grigory Andreychev

We provide a geometric-combinatorial model for the category of coherent sheaves on the weighted projective line of type (2,2,n) via a cylindrical surface with n marked points on each of its upper and lower boundaries, equipped with an order…

Representation Theory · Mathematics 2025-01-15 Jianmin Chen , Jinfeng Zhang

We consider a hyperplane arrangement in $\mathbb{C}^n$ defined over $\mathbb{R}$, and the associated natural stratification of $\mathbb{C}^n$. The category of perverse sheaves smooth with respect to this stratification was described by…

Representation Theory · Mathematics 2020-11-17 Asilata Bapat

For a particular class of pseudo manifolds, we show that the intersection cohomology groups for any perversity may be naturally represented by extended weighted $L^2$ harmonic forms for a complete metric on the regular stratum with respect…

Geometric Topology · Mathematics 2017-01-12 E. Hunsicker

We study full exact functors between triangulated categories. With some hypotheses on the source category we prove that it admits an orthogonal decomposition into two pieces such that the functor restricted to one of them is zero while the…

Algebraic Geometry · Mathematics 2013-12-10 Alberto Canonaco , Dmitri Orlov , Paolo Stellari

In their article "Elementary construction of perverse sheaves", R.MacPherson and K. Vilonen show that on a Thom-Mather space X the category PervX of perverse sheaves is equivalent to the category C(F, G, T) whose objects are data of…

Algebraic Geometry · Mathematics 2011-03-23 Delphine Dupont

Hearts of cotorsion pairs on extriangulated categories are abelian categories. On the other hand, hearts of twin cotorsion pairs are not always abelian. They were shown to be semi-abelian by Liu and Nakaoka. Moreover, Hassoun and Shah…

Representation Theory · Mathematics 2025-06-25 Yu Liu , Wuzhong Yang , Panyue Zhou

This paper classifies t-structures on the local derived category of a 3-fold flopping contraction, that are intermediate with respect to the heart of perverse coherent sheaves. Equivalently, this describes the complete lattice of torsion…

Algebraic Geometry · Mathematics 2026-03-09 Parth Shimpi

We define the countable Rouquier dimension of a triangulated category and use this notion together with Theorem 2 of [Ola21] to prove that if there is a fully faithful embedding $D^b_{coh}(X) \subset D^b_{coh}(Y)$ with $X, Y$ smooth proper…

Algebraic Geometry · Mathematics 2021-10-19 Noah Olander

The method of intersection spaces associates rational Poincar\'e complexes to singular stratified spaces. For a conifold transition, the resulting cohomology theory yields the correct count of all present massless 3-branes in type IIB…

Algebraic Geometry · Mathematics 2016-05-24 Markus Banagl , Nero Budur , Laurentiu Maxim

The first part of this article is devoted to characterizing the cocycles $\alpha$ of a finite group $G$ that give rise to faithful projective representations of $G$. We prove that a $p$-group $G$ admits a faithful irreducible projective…

Representation Theory · Mathematics 2026-05-27 Sumana Hatui , Poonam Nayak