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Given an open-closed decomposition of the stratifying poset, we construct a new semi-orthogonal decomposition of the $\infty$-category of constructible sheaves on a stratified space admitting an exit-path $\infty$-category. From this we…

K-Theory and Homology · Mathematics 2026-02-24 Qingyuan Bai , Peter J. Haine

Given a proper morphism X -> S, we show that a large class of objects in the derived category of X naturally form an Artin stack locally of finite presentation over S. This class includes S-flat coherent sheaves and, more generally,…

Algebraic Geometry · Mathematics 2018-06-18 Max Lieblich

We prove smoothness in the dg sense of the bounded derived category of finitely generated modules over any finite-dimensional algebra over a perfect field, hereby answering a question of Iyama. More generally, we prove this statement for…

Algebraic Geometry · Mathematics 2019-03-25 Alexey Elagin , Valery A. Lunts , Olaf M. Schnürer

We show that the hypercohomology of most character twists of perverse sheaves on a complex abelian variety vanishes in all non-zero degrees. As a consequence we obtain a vanishing theorem for constructible sheaves and a relative vanishing…

Algebraic Geometry · Mathematics 2015-10-01 Thomas Krämer , Rainer Weissauer

Studying crepant blow-ups of (compound) du Val singularities, we classify complexes of coherent sheaves which admit no negative self-extensions -- such a complex, up to flops and mutation equivalences, must either be (1) a module over a…

Algebraic Geometry · Mathematics 2025-08-11 Parth Shimpi

We propose a geometric and categorical approach to the Hodge Conjecture for all smooth projective complex varieties. By embedding any such variety into a flat family with general fibers smooth complete intersections, we prove the conjecture…

Algebraic Geometry · Mathematics 2025-08-15 Karim Mansour

The purpose of this note is to give a short proof of a theorem of Koll\'ar that the derived direct image of the canonical sheaf splits into a sum of its cohomology sheaves. This is deduced from a stronger decomposition theorem for direct…

Algebraic Geometry · Mathematics 2013-09-16 Donu Arapura

We show that the derived category of coherent sheaves on the quotient stack of the affine plane by a finite small subgroup of the general linear group is obtained from the derived category of coherent sheaves on the minimal resolution by…

Algebraic Geometry · Mathematics 2013-09-23 Akira Ishii , Kazushi Ueda

Let X be a quasi-compact and quasi-separated (not necessarily semiseparated) scheme. The category QcoX of all quasi-coherent sheaves of OX-modules has several diferent pure derived categories. Recently, categorical pure derived categories…

Algebraic Geometry · Mathematics 2019-01-29 Esmaeil Hosseini

(Makes a Gamma-acylic coherent resolution of a coherent sheaf on a projection scheme.)

alg-geom · Mathematics 2008-02-03 George R. Kempf

We give a motivated introduction to the theory of perverse sheaves, culminating in the Decomposition Theorem of Beilinson, Bernstein, Deligne and Gabber. A goal of this survey is to show how the theory develops naturally from classical…

Algebraic Geometry · Mathematics 2009-04-16 Mark Andrea de Cataldo , Luca Migliorini

The goal of this paper is to prove: if certain 'standard' conjectures on motives over algebraically closed fields hold, then over any 'reasonable' $S$ there exists a motivic $t$-structure for the category of Voevodsky's $S$-motives (as…

Algebraic Geometry · Mathematics 2015-05-27 Mikhail V. Bondarko

We prove that the bounded derived category of coherent sheaves on a smooth projective complex variety reconstructs the isomorphism classes of fibrations onto smooth projective curves of genus $g\geq 2$. Moreover, in dimension at most four,…

Algebraic Geometry · Mathematics 2023-09-14 Luigi Lombardi

We prove uniform boundedness statements for semistable pure sheaves on projective manifolds. For example, we prove that the set of isomorphism classes of pure sheaves of dimension 2 that are slope semistable with respect to ample classes…

Algebraic Geometry · Mathematics 2024-03-20 Mihai Pavel , Julius Ross , Matei Toma

Cohomology of a compatible family of Lie algebroids defined on a family of transverse manifolds is defined. A sheaf of differential forms on a compatible family of Lie algebroids defined over regular open subsets of a simplicial complex is…

Algebraic Topology · Mathematics 2018-02-20 Jose R. Oliveira

We construct a semiorthogonal decomposition of the derived category of coherent sheaves on a quadric fibration consisting of several copies of the derived category of the base of the fibration and the derived category of coherent sheaves of…

Algebraic Geometry · Mathematics 2007-05-23 Alexander Kuznetsov

We assume given a smooth symplectic (in the algebraic sense) resolution $X$ of an affine algebraic variety $Y$, and we prove that, possibly after replacing $Y$ with an etale neighborhood of a point, the derived category of coherent sheaves…

Algebraic Geometry · Mathematics 2007-05-23 D. Kaledin

In this paper, we extend the structure theorem for smooth projective varieties with nef tangent bundle to projective klt varieties whose tangent sheaf is either positively curved or almost nef. Specifically, we show that such a variety $X$,…

Algebraic Geometry · Mathematics 2025-07-23 Masataka Iwai , Shin-ichi Matsumura , Guolei Zhong

We investigate the behavior of semi-orthogonal decompositions of bounded derived categories of singular varieties under flat deformations to smooth varieties. We consider a Q-Gorenstein smoothing of a surface with a quotient singularity,…

Algebraic Geometry · Mathematics 2024-10-22 Yujiro Kawamata

We interpret some results of persistent homology and barcodes (in any dimension) with the language of microlocal sheaf theory. For that purpose we study the derived category of sheaves on a real finite-dimensional vector space V. By using…

Algebraic Topology · Mathematics 2018-09-10 Masaki Kashiwara , Pierre Schapira