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Related papers: Cdh descent, cdarc descent, and Milnor excision

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We construct a semi-orthogonal decomposition on the category of perfect complexes on the blow-up of a derived Artin stack in a quasi-smooth centre. This gives a generalization of Thomason's blow-up formula in algebraic K-theory to derived…

K-Theory and Homology · Mathematics 2020-09-15 Adeel A. Khan

We prove a blow-up formula for cyclic homology which we use to show that infinitesimal $K$-theory satisfies $cdh$-descent. Combining that result with some computations of the $cdh$-cohomology of the sheaf of regular functions, we verify a…

K-Theory and Homology · Mathematics 2011-08-03 G. Cortiñas , C. Haesemeyer , M. Schlichting , C. A. Weibel

We prove that the $\infty$-category of motivic spectra satisfies Milnor excision: if $A\to B$ is a morphism of commutative rings sending an ideal $I\subset A$ isomorphically onto an ideal of $B$, then a motivic spectrum over $A$ is…

Algebraic Geometry · Mathematics 2021-08-06 Elden Elmanto , Marc Hoyois , Ryomei Iwasa , Shane Kelly

We construct geometric models for classifying spaces of linear algebraic groups in G-equivariant motivic homotopy theory, where G is a tame group scheme. As a consequence, we show that the equivariant motivic spectrum representing the…

K-Theory and Homology · Mathematics 2020-09-16 Marc Hoyois

Let X be a smooth variety over a field k and D an effective divisor whose support has simple normal crossings. We construct an explicit cycle map from the r-th Nisnevich motivic complex of the pair (X,D) to a shift of the r-th relative…

Algebraic Geometry · Mathematics 2016-07-13 Kay Rülling , Shuji Saito

We introduce a pro-cdh topology on formal schemes and prove that the $\infty$-topos of pro-cdh sheaves of spaces has an optimal bound of homotopy dimension. This remedies a defect for a pro-cdh topology on schemes introduced in [KS23]. As…

Algebraic Geometry · Mathematics 2024-09-24 Shane Kelly , Shuji Saito

Grothendieck's formal functions theorem states that the coherent cohomology of a Noetherian scheme can be recovered from that of a blowup and the infinitesimal thickenings of the center and of the exceptional divisor of the blowup. In this…

K-Theory and Homology · Mathematics 2026-01-21 Shane Kelly , Shuji Saito , Georg Tamme

In this article we propose a definition of a procdh topos. We show that it encodes procdh excision, has bounded homotopy dimension and therefore is hypercomplete and admits a conservative family of fibre functors. We also describe the local…

Algebraic Geometry · Mathematics 2024-01-08 Shane Kelly , Shuji Saito

Voevodsky outlined a conjectural programme that his slice filtration in motivic homotopy theory should give rise to a good theory of $\mathbb{A}^1$-invariant motivic cohomology. This paper achieves his vision in the generality of arbitrary…

K-Theory and Homology · Mathematics 2025-08-14 Tom Bachmann , Elden Elmanto , Matthew Morrow

We develop the theory of Milnor-Witt motives and motivic cohomology. Compared to Voevodsky's theory of motives and his motivic cohomology, the first difference appears in our definition of Milnor-Witt finite correspondences, where our…

Algebraic Geometry · Mathematics 2022-04-05 Tom Bachmann , Baptiste Calmès , Frédéric Déglise , Jean Fasel , Paul Arne Østvær

We consider Voevodsky's slice tower for a finite spectrum E in the motivic stable homotopy category over a perfect field k. In case k has finite cohomological dimension (in characteristic two, we also require that k is infinite), we show…

Algebraic Geometry · Mathematics 2013-03-08 Marc Levine

For $E$ a presheaf of spectra on the category of smooth $k$-schemes satisfying Nisnevich excision, we prove that the canonical map from the algebraic singular complex of the theory $E$ with quasi-finite supports to the theory $E$ with…

K-Theory and Homology · Mathematics 2012-07-12 Joseph Ross

We show that equivariant K-theory satisfies descent with respect to the isovariant Nisnevich topology. The main step is to show that the isovariant Nisnevich topology is a regular, complete and bounded cd topology.

K-Theory and Homology · Mathematics 2010-02-15 Christian Serpe

We construct a motivic spectral sequence for the relative homotopy invariant K-theory of a closed immersion of schemes $D \subset X$. The $E_2$-terms of this spectral sequence are the cdh-hypercohomology of a complex of equi-dimensional…

Algebraic Geometry · Mathematics 2019-03-13 Amalendu Krishna , Pablo Pelaez

A continuous map C^d -> C^N is a complex k-regular embedding if any k pairwise distinct points in C^d are mapped by f into k complex linearly independent vectors in C^N. Our central result on complex k-regular embeddings extends results of…

Algebraic Topology · Mathematics 2015-10-28 Pavle V. M. Blagojević , Frederick R. Cohen , Wolfgang Lück , Günter M. Ziegler

We introduce a Bredon motivic cohomology theory for smooth schemes defined over a field and equipped with an action by a finite group. These cohomology groups are defined for finite dimensional representations as the hypercohomology of…

Algebraic Geometry · Mathematics 2014-08-12 Jeremiah Heller , Mircea Voineagu , Paul Arne Ostvaer

We prove, for quasicompact separated schemes over ground fields, that Cech cohomology coincides with sheaf cohomology with respect to the Nisnevich topology. This is a partial generalization of Artin's result that for noetherian schemes…

Algebraic Geometry · Mathematics 2017-06-14 Stefan Schröer

We prove the excision theorem for the $K$-theory of perfect complexes on Deligne-Mumford stacks. This is then used to study the Nisnevich site of such stacks. We prove the Nisnevich descent for the $K$-theory of perfect complexes. We also…

Algebraic Geometry · Mathematics 2010-05-07 Amalendu Krishna , Paul-Arne Ostvaer

In this paper we prove that cyclic homology, topological cyclic homology, and algebraic $K$-theory satisfy a pro Mayer--Vietoris property with respect to abstract blow-up squares of varieties, in both zero and finite characteristic. This…

K-Theory and Homology · Mathematics 2019-02-20 Matthew Morrow

We study the algebraic $K$-theory of smooth schemes over $W_n(\Bbbk)$, where $\Bbbk$ is a perfect field of characteristic $p>0$. For a $p$-adic smooth scheme $X_{\centerdot}$ over $W_{\centerdot}(k)$, we introduce complexes…

Algebraic Geometry · Mathematics 2026-02-24 Xiaowen Hu
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