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Let K be an Abstract Elementary Class. Under the asusmptions that K has a nicely behaved forking-like notion, regular types and existence of some prime models we establish a decomposition theorem for such classes. The decomposition implies…

Logic · Mathematics 2007-05-23 Rami Grossberg , Olivier Lessmann

We develop the deformation-obstruction calculus for morphisms of complexes with a fixed lift of the codomain, to derived categories of flat nilpotent deformations of abelian categories. As an application, we give an alternative proof that…

Algebraic Geometry · Mathematics 2025-11-14 Pieter Belmans , Wendy Lowen , Shinnosuke Okawa , Andrea T. Ricolfi

We give a classification of all exact structures on a given idempotent complete additive category. Using this, we investigate the structure of an exact category with finitely many indecomposables. We show that the relation of the…

Representation Theory · Mathematics 2019-07-30 Haruhisa Enomoto

We show that for quasi-compact quasi-separated schemes of finite dimension, the constructibility condition in real \'etale cohomology agrees with a notion of constructibility arising naturally from topology. As application we prove that the…

Algebraic Geometry · Mathematics 2022-01-04 Fangzhou Jin

We show how natural functors from the category of coherent sheaves on a projective scheme to categories of Kronecker modules can be used to construct moduli spaces of semistable sheaves. This construction simplifies or clarifies technical…

Algebraic Geometry · Mathematics 2009-11-11 Luis Álvarez-Cónsul , Alastair King

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 show that bounded type implies finite type for a constructible subcategory of the module category of a finitely generated algebra over a field, which is a variant of the first Brauer-Thrall conjecture. A full subcategory is constructible…

Representation Theory · Mathematics 2025-07-31 Kevin Schlegel , Andres Fernandez Herrero

It is proved that the sum of the Loewy lengths of the homology modules of a finite free complex F over a local ring R is bounded below by a number depending only on R. This result uncovers, in the structure of modules of finite projective…

Commutative Algebra · Mathematics 2010-05-20 L. L. Avramov , R. -O. Buchweitz , S. B. Iyengar , C. Miller

We show how to use the combinatorial notion of jump sets to parametrize the possible structures of the group of principal units of local fields, viewed as filtered modules. We establish a natural bijection between the set of jump sets and…

Number Theory · Mathematics 2018-10-24 Carlo Pagano

We prove a general vanishing theorem for the cohomology of products of symmetric and skew-symmetric powers of an ample vector bundle on a smooth complex projective variety. Special cases include an extension of classical theorems of…

alg-geom · Mathematics 2009-10-28 Laurent Manivel

We introduce a class of toposes called "absolutely locally compact" toposes and of "admissible" sheaf of rings over such toposes. To any such ringed topos $(\mathcal{T},A)$ we attach an involutive convolution algebra…

Category Theory · Mathematics 2017-01-03 Simon Henry

We present a detailed introduction of the theory of constructible sheaf complexes in the complex algebraic and analytic setting. All concepts are illustrated by many interesting examples and relevant applications, while some important…

Algebraic Geometry · Mathematics 2021-06-03 Laurenţiu G. Maxim , Jörg Schürmann

We give a moduli-theoretic proof of the classical theorem of Gabriel, stating that a scheme can be reconstructed from the abelian category of quasi-coherent sheaves over it. The methods employed are elementary and allow us to extend the…

Algebraic Geometry · Mathematics 2013-10-25 John Calabrese , Michael Groechenig

We define a new geometric object--the stack of local systems with restricted variation. We formulate a version of the categorical geometric Langlands conjecture that makes sense for any constructible sheaf theory (such as l-adic sheaves).…

Algebraic Geometry · Mathematics 2022-04-07 D. Arinkin , D. Gaitsgory , D. Kazhdan , S. Raskin , N. Rozenblyum , Y. Varshavsky

We establish a structure theorem on the arc space of a $k$-scheme of finite type. More precisely, we show that the arc space is locally for the pro-smooth toplogy a product of an infinite dimensional affine space and of a non-noetherian…

Algebraic Geometry · Mathematics 2020-08-18 Alexis Bouthier

In this paper, we prove that any perfect complex of $D^{\infty}$-modules may be reconstructed from its holomorphic solution complex provided that we keep track of the natural topology of this last complex. This is to be compared with the…

Algebraic Geometry · Mathematics 2007-05-23 F. Prosmans , J. -P. Schneiders

According to Laumon, an affine Springer fiber is homeomorphic to the universal abelian covering of the compactified Jacobian of a spectral curve. We construct equivariant deformations $f_{n}:\overline{\mathcal{P}}_{n}\to \mathcal{B}_{n}$ of…

Algebraic Geometry · Mathematics 2024-04-15 Zongbin Chen

The higher direct image complex of a coherent sheaf (or finite complex of coherent sheaves) under a projective morphism is a fundamental construction that can be defined via a Cech complex or an injective resolution, both inherently…

Algebraic Geometry · Mathematics 2007-05-23 David Eisenbud , Frank-Olaf Schreyer

Suppose we are given complex manifolds $X$ and $Y$ together with substacks $\mathcal{S}$ and $\mathcal{S}'$ of modules over algebras of formal deformation $\mathcal{A}$ on $X$ and $\mathcal{A}'$ on $Y$, respectively. Suppose also we are…

Algebraic Geometry · Mathematics 2013-01-10 Ana Rita Martins , Teresa Monteiro Fernandes , David Raimundo

We prove that the length function for perverse sheaves and algebraic regular holonomic D-modules on a smooth complex algebraic variety Y is an absolute Q-constructible function. One consequence is: for "any" fixed natural (derived) functor…

Algebraic Geometry · Mathematics 2019-03-14 Nero Budur , Pietro Gatti , Yongqiang Liu , Botong Wang