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On \'etudie les cycles alg\'ebriques de codimension 3 sur les hypersurfaces cubiques lisses de dimension 5. Pour une telle hypersurface, on d\'emontre d'une part que son groupe de Griffiths des cycles de codimension 3 est trivial et d'autre…

Algebraic Geometry · Mathematics 2018-11-08 Lie Fu , Zhiyu Tian

We use techniques of Alper-Hall-Rydh to prove a local structure theorem for smooth morphisms between smooth stacks around points with linearly reductive stabilizers. This implies that the good moduli space of a smooth stack over a base has…

Algebraic Geometry · Mathematics 2026-05-12 Mark Andrea de Cataldo , Andres Fernandez Herrero , Andrés Ibáñez Núñez

Let G be a real or complex linear algebraic reductive group. Let H and F be reductive subgroups. We study the natural H action on G/F. The main theorem of this note shows that generic H orbits are closed. This theorem is then applied to…

Algebraic Geometry · Mathematics 2008-06-09 M. Jablonski

We consider two cycles on the moduli space of compact type curves and prove that they coincide. The first is defined by pushing forward the virtual fundamental classes of spaces of relative stable maps to an unparameterized rational curve,…

Algebraic Geometry · Mathematics 2013-10-23 Steffen Marcus , Jonathan Wise

We give a local characterization for when certain quiver representations in semisimple Abelian categories are semisimple, among them those arising from degenerations of linear series. This paper is the first of two, aimed to describe all…

Algebraic Geometry · Mathematics 2025-12-30 Eduardo Esteves , Renan Santos , Eduardo Vital

We define abelian extensions of algebras in congruence-modular varieties. The theory is sufficiently general that it includes, in a natural way, extensions of R-modules for a ring R. We also define a cohomology theory, which we call clone…

Rings and Algebras · Mathematics 2007-05-23 William H. Rowan

For any type of fundamental groupoid scheme, we construct an algebraic cohomology theory for varieties with coefficients in the base field. This is a minor variant of \'etale cohomology, involving neither de Rham complexes nor…

Algebraic Geometry · Mathematics 2026-02-16 Hyuk Jun Kweon

As an application of the theory of Lawson homology and morphic cohomology, Walker proved that the Abel-Jacobi map factors through another regular homomorphism. In this note, we give a direct proof of the theorem.

Algebraic Geometry · Mathematics 2025-01-08 Fumiaki Suzuki

In this paper, first we give the notion of a representation of a relative Rota-Baxter Lie algebra and introduce the cohomologies of a relative Rota-Baxter Lie algebra with coefficients in a representation. Then we classify abelian…

Representation Theory · Mathematics 2022-04-08 Jun Jiang , Yunhe Sheng

We axiomatically define (pre-)Hilbert categories. The axioms resemble those for monoidal Abelian categories with the addition of an involutive functor. We then prove embedding theorems: any locally small pre-Hilbert category whose monoidal…

Category Theory · Mathematics 2010-08-05 Chris Heunen

Reflexive functors of modules naturally appear in Algebraic Geometry. In this paper we define a wide and elementary family of reflexive functors of modules, closed by tensor products and homomorphisms, in which Algebraic Geometry can be…

Algebraic Geometry · Mathematics 2015-11-16 Pedro Sancho

We establish a connection between certain unique models, or equivalently unique functionals, for representations of p-adic groups and linear characters of their corresponding Hecke algebras. This allows us to give a uniform evaluation of…

Representation Theory · Mathematics 2015-07-29 Ben Brubaker , Daniel Bump , Solomon Friedberg

In SGA3, Demazure and Grothendieck showed that if $G$ and $H$ are smooth affine group schemes over a scheme $S$ and $G$ is reductive, then the functor of $S$-homomorphism $G \to H$ is representable. In this paper we extend this result to…

Algebraic Geometry · Mathematics 2025-11-19 Sean Cotner

Consider the functor describing deformations of a representation of the fundamental group of a variety X. This paper is chiefly concerned with establishing an analogue in finite characteristic of a result proved by Goldman and Millson for…

Algebraic Geometry · Mathematics 2019-07-04 J. P. Pridham

We introduce jacobian graphs, which are explicit families of regular graphs that are spectrally indistinguishable from random graphs, but whose local structure is very different from that of random graphs. The construction relies on the…

Number Theory · Mathematics 2026-03-16 Arthur Forey , Javier Fresán , Emmanuel Kowalski , Yuval Wigderson

This paper is about the question whether a cycle in the l-adic cohomology of a smooth projective variety over the rational numbers, which is algebraic over almost all finite fields, is also algebraic over the rationals. We use ultraproducts…

Algebraic Geometry · Mathematics 2009-02-02 Lars Brünjes , Christian Serpé

The Reeb graph of a smooth function is a graph being a natural quotient space of the manifold of the domain and the space of all connected components of preimages. Such a combinatorial and topological object roughly and compactly represents…

Algebraic Geometry · Mathematics 2023-08-10 Naoki Kitazawa

We prove analogues of several well-known results concerning rational morphisms between quadrics for the class of so-called quasilinear $p$-hypersurfaces. These hypersurfaces are nowhere smooth over the base field, so many of the geometric…

Algebraic Geometry · Mathematics 2013-11-19 Stephen Scully

We extend the category of (super)manifolds and their smooth mappings by introducing a notion of microformal or "thick" morphisms. They are formal canonical relations of a special form, constructed with the help of formal power expansions in…

Differential Geometry · Mathematics 2019-01-08 Theodore Voronov

Let X be a smooth complex algebraic variety. Morgan [Mor78] showed that the rational homotopy type of X is a formal consequence of the differential graded algebra defined by the first term of its weight spectral sequence. In the present…

Algebraic Geometry · Mathematics 2014-11-26 J. Cirici , F. Guillén