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We show that two different possible theories of Nori motivic sheaves, introduced by Ivorra--Morel and by Ayoub, respectively, are canonically equivalent. The proof of this result, which exploits the six functor formalism systematically, is…

Algebraic Geometry · Mathematics 2026-02-10 Emil Jacobsen , Luca Terenzi

We define an unstable equivariant motivic homotopy category for an algebraic group over a Noetherian base scheme. We show that equivariant algebraic $K$-theory is representable in the resulting homotopy category. Additionally, we establish…

Algebraic Topology · Mathematics 2015-10-19 Jeremiah Heller , Amalendu Krishna , Paul Arne Ostvaer

Let G be an infinitesimal group scheme of finite height r and V(G) the scheme which represents 1-parameter subgroups of G. We consider sheaves over the projectivization P(G) of V(G) constructed from a G-module M. We show that if P(G) is…

Representation Theory · Mathematics 2015-04-01 Jim Stark

We construct the motivic t-structure on 1-motives with integral coefficients over a scheme of characteristic zero or a Dedekind scheme. When we invert the residue characteristic exponents of the base, this t-structure induces a t-structure…

Algebraic Geometry · Mathematics 2025-06-13 Raphaël Ruimy

The apparatus of motivic stable homotopy theory provides a notion of Euler characteristic for smooth projective varieties, valued in the Grothendieck-Witt ring of the base field. Previous work of the first author and recent work of…

Algebraic Geometry · Mathematics 2020-08-26 Marc Levine , Arpon Raksit

For a non-isotrivial family of surfaces of general type over a complex projective curve, we give upper bounds for the degree of the direct images of powers of the relative dualizing sheaf. They imply that, fixing the curve and the possible…

Algebraic Geometry · Mathematics 2009-10-31 E. Bedulev , E. Viehweg

We define a motivic conductor for any presheaf with transfers $F$ using the categorical framework developed for the theory of motives with modulus by Kahn-Miyazaki-Saito-Yamazaki. If $F$ is a reciprocity sheaf this conductor yields an…

Algebraic Geometry · Mathematics 2021-07-01 Kay Rülling , Shuji Saito

We introduce a direct image formalism for constructible motivic functions. One deduces a very general version of motivic integration for which a change of variables theorem is proved. These constructions are generalized to the relative…

Algebraic Geometry · Mathematics 2007-05-23 R. Cluckers , F. Loeser

We introduce coefficient systems of pro-\'etale motives and pro-\'etale motivic spectra with coefficients in any condensed ring spectrum and show that they afford the six operations. Over locally \'etale bounded schemes, \'etale motivic…

Algebraic Geometry · Mathematics 2026-04-03 Raphaël Ruimy , Swann Tubach , Sebastian Wolf

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 give a criterion for the projectivisation of a reflexive sheaf on a klt space to be induced by a projective representation of the fundamental group of the smooth locus. This criterion is then applied to give a characterisation of finite…

Algebraic Geometry · Mathematics 2022-07-25 Daniel Greb , Stefan Kebekus , Thomas Peternell

We construct smooth presentations of algebraic stacks that are local epimorphisms in the Morel-Voevodsky $\mathbb{A}^1$-homotopy category. As a consequence we show that the motive of a smooth stack (in Voevodsky's triangulated category of…

Algebraic Geometry · Mathematics 2025-01-28 Neeraj Deshmukh , Jack Hall

Let S be a Noetherian scheme and f:X -> S a proper morphism. By SGA 4 XIV, for any constructible sheaf F of Z/nZ-modules on X, the sheaves of Z/nZ-modules R^if_*F obtained by direct image (for the etale topology) are also constructible:…

Algebraic Geometry · Mathematics 2019-03-27 Fabrice Orgogozo

We show that the derived category of perverse Nori motives and mixed Hodge modules are the derived categories of their constructible hearts. This enables us to construct $\infty$-categorical lifts of the six operations and therefore to…

Algebraic Geometry · Mathematics 2025-10-15 Swann Tubach

In this series of papers, we propose a theory of enumerative invariants counting self-dual objects in self-dual categories. Ordinary enumerative invariants in abelian categories can be seen as invariants for the structure group $\mathrm{GL}…

Algebraic Geometry · Mathematics 2025-04-01 Chenjing Bu

We develop a "Soergel theory" for Bruhat-constructible perverse sheaves on the flag variety $G/B$ of a complex reductive group $G$, with coefficients in an arbitrary field $\Bbbk$. Namely, we describe the endomorphisms of the projective…

Representation Theory · Mathematics 2020-02-19 Roman Bezrukavnikov , Simon Riche

We describe the closure of the strata of abelian differentials with prescribed type of zeros and poles, in the projectivized Hodge bundle over the Deligne-Mumford moduli space of stable curves with marked points. We provide an explicit…

Algebraic Geometry · Mathematics 2018-11-14 Matt Bainbridge , Dawei Chen , Quentin Gendron , Samuel Grushevsky , Martin Moeller

We study the 0-th stable A^1-homotopy sheaf of a smooth proper variety over a field k assumed to be infinite, perfect and to have characteristic unequal to 2. We provide an explicit description of this sheaf in terms of the theory of…

Algebraic Geometry · Mathematics 2011-08-22 Aravind Asok , Christian Haesemeyer

The motivic homotopy categories can be defined with respect to different topologies and different underlying categories of schemes. For a number of reasons (mainly because of the Gluing Theorem) the motivic homotopy category built out of…

Algebraic Geometry · Mathematics 2008-05-30 Vladimir Voevodsky

We give a new proof of the Mordell-Lang conjecture in positive characteristic, in the situation where the variety under scrutiny is a smooth subvariety of an abelian variety. Our proof is based on the theory of semistable sheaves in…

Algebraic Geometry · Mathematics 2018-02-16 Damian Rössler
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