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In the paper we answer the following question: for a morphism of varieties (or, more generally, stacks), when the derived category of the base can be recovered from the derived category of the covering variety by means of descent theory? As…

Algebraic Geometry · Mathematics 2015-05-27 Alexey Elagin

In this paper, we introduce the classification of equivariant principal bundles over the 2-sphere. Isotropy representations provide tools for understanding the classification of equivariant principal bundles. We consider a…

Geometric Topology · Mathematics 2024-03-04 Eyup Yalcinkaya

Given a Noetherian formal scheme $\hat X$ over ${\rm Spf}(R)$, where $R$ is a complete DVR, we first prove a theorem of meromorphic descent along a possibly infinite cover of $\hat{X}$. Using this we construct a specialization functor from…

Algebraic Geometry · Mathematics 2022-02-08 Marcin Lara , Jiu-Kang Yu , Lei Zhang

We introduce a notion of equivariant vector bundles on schemes over semirings. We do this by considering the functor of points of a locally free sheaf. We prove that every toric vector bundle on a toric scheme $X$ over an idempotent…

Algebraic Geometry · Mathematics 2025-07-30 Jaiung Jun , Kalina Mincheva , Jeffrey Tolliver

We strengthen the maximal ergodic theorem for actions of groups of polynomial growth to a form involving jump quantity, which is the sharpest result among the family of variational or maximal ergodic theorems. As a consequence, we deduce in…

Dynamical Systems · Mathematics 2026-01-14 Guixiang Hong , Wei Liu

We prove a refinement of the Grothendieck-Riemann-Roch theorem in degree one.

Algebraic Geometry · Mathematics 2019-04-09 Damian Rössler

We prove the existence of tilting bundles on global quotient stacks that are produced by compatible finite group actions on flat families.

Algebraic Geometry · Mathematics 2015-11-24 Saša Novaković

We define functorial isomorphisms of parallel transport along \'etale paths for a class of principal $G$-bundles on a $p$-adic curve. Here $G$ is a connected reductive algebraic group of finite presentation and the considered principal…

Algebraic Geometry · Mathematics 2007-06-08 Urs Hackstein

We use the formalism of traces in higher categories to prove a common generalization of the holomorphic Atiyah-Bott fixed point formula and the Grothendieck-Riemann-Roch theorem. The proof is quite different from the original one proposed…

Algebraic Geometry · Mathematics 2019-06-27 Grigory Kondyrev , Artem Prikhodko

We show that in a smooth family of complete varieties, the existence of full exceptional collection on a fiber preserves for the fibers in a neighborhood. Then we show that the noncommutative deformations of a strong exceptional collection…

Algebraic Geometry · Mathematics 2019-03-08 Xiaowen Hu

We construct a family of rings. To a plane diagram of a tangle we associate a complex of bimodules over these rings. Chain homotopy equivalence class of this complex is an invariant of the tangle. On the level of Grothendieck groups this…

Quantum Algebra · Mathematics 2014-10-01 Mikhail Khovanov

We develop the theory of simplicial extensions for bundle gerbes and their characteristic classes with a view towards studying descent problems and equivariance for bundle gerbes. Equivariant bundle gerbes are important in the study of…

Differential Geometry · Mathematics 2018-02-02 Michael K. Murray , David Michael Roberts , Danny Stevenson , Raymond F. Vozzo

The Graded Classification Conjecture (GCC) states that the pointed $K_0^{\operatorname{gr}}$-group is a complete invariant of the Leavitt path algebras of finite graphs when these algebras are considered with their natural grading by…

Rings and Algebras · Mathematics 2026-03-03 Lia Vas

In this paper a method of constructing a semiorthogonal decomposition of the derived category of $G$-equivariant sheaves on a variety $X$ is described, provided that the derived category of sheaves on $X$ admits a semiorthogonal…

Algebraic Geometry · Mathematics 2015-10-22 Alexey Elagin

In this paper, we view the equivariant orientation theory of equivariant vector bundles from the lenses of equivariant Picard spectra. This viewpoint allows us to identify, for a finite group $\mathrm{G}$, a precise condition under which an…

Algebraic Topology · Mathematics 2024-09-24 Prasit Bhattacharya , Foling Zou

We give a direct combinatorial proof that the product of two descent classes in a symmetric group is a sum of descent classes. The proof is based on the fact that the group product gives a covering map when descent classes are endowed with…

Combinatorics · Mathematics 2025-06-09 Philippe Biane

Let $G$ be a connected reductive algebraic group. Let $\mathcal{E}\rightarrow \mathcal{B}$ be a principal $G\times G$-bundle and $X$ be a regular compactification of $G$. We describe the Grothendieck ring of the associated fibre bundle…

Algebraic Geometry · Mathematics 2020-08-25 V. Uma

This is a continuation of the authors' previous work [math.AT/9910001] on classification of equivariant complex vector bundles over a circle. In this paper we classify equivariant real vector bundles over a circle with a compact Lie group…

Algebraic Topology · Mathematics 2023-10-31 Jin-Hwan Cho , Sung Sook Kim , Mikiya Masuda , Dong Youp Suh

In this work, generalized principal bundles modelled by Lie group bundle actions are investigated. In particular, the definition of equivariant connections in these bundles, associated to Lie group bundle connections, is provided, together…

Differential Geometry · Mathematics 2023-03-10 Marco Castrillón López , Álvaro Rodríguez Abella

We construct Euler and Stiefel-Whitney classes of vector bundles with quadratic form by analyzing the intersection theory of the associated quadric bundles. We also compute the Chow rings of quadric and isotropic flag bundles. Along the…

alg-geom · Mathematics 2008-02-03 D. Edidin , W. Graham