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We view strict ring spectra as generalized rings. The study of their algebraic K-theory is motivated by its applications to the automorphism groups of compact manifolds. Partial calculations of algebraic K-theory for the sphere spectrum are…

Algebraic Topology · Mathematics 2022-06-22 John Rognes

We define bivariant algebraic K-theory and bivariant derived Chow on the homotopy category of derived schemes over a smooth base. The orientation on the latter corresponds to virtual Gysin homomorphisms. We then provide a morphism between…

Algebraic Geometry · Mathematics 2012-09-03 Parker Lowrey , Timo Schürg

We prove that for every reductive algebraic group $H$ with centre of positive dimension and every integer $K$ there is a smooth and projective variety $X$ and an algebraic $H$-torsor $P \to X$ such that the classifying map $X \to \Bclass H$…

Algebraic Geometry · Mathematics 2009-05-12 Torsten Ekedahl

We prove that singular cohomology of the underlying space of Berkovich's analytification of a scheme $X$ locally of finite type over a trivially-valued field $k$ of characteristic $0$ is isomorphic to cdh-cohomology with integer…

Algebraic Geometry · Mathematics 2024-11-28 Semen Molokov , Vadim Vologodsky

The classical arithmetic Grothendieck-Riemann-Roch theorem can be applied only to projective morphisms that are smooth over the complex numbers. In this paper we generalize the arithmetic Grothendieck-Riemann-Roch theorem to the case of…

Algebraic Geometry · Mathematics 2012-11-09 José Ignacio Burgos Gil , Gerard Freixas i Montplet , Razvan Litcanu

Let k be an algebraically closed field of characteristic 0, and let f be a morphism of smooth projective varieties from X to Y over the ring k((t)) of formal Laurent series. We prove that if a general geometric fiber of f is rationally…

Algebraic Geometry · Mathematics 2016-06-28 Morgan Brown , Tyler Foster

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

Let X be a Noetherian scheme of finite dimension and denote by rho the (additive inverse of the) morphism in SH(X) from S to Gm corresponding to the unit -1. Here SH(X) denotes the motivic stable homotopy category. We show that the category…

K-Theory and Homology · Mathematics 2019-02-20 Tom Bachmann

The aim of this paper is to connect two important and apparently unrelated theories: motivic homotopy theory and ramification theory. We construct motivic homotopy categories over a qcqs base scheme $S$, in which cohomology theories with…

Algebraic Geometry · Mathematics 2025-04-04 Junnosuke Koizumi , Hiroyasu Miyazaki , Shuji Saito

We establish fundamental motivic results about hermitian K-theory without assuming that 2 is invertible on the base scheme. In particular, we prove that both quadratic and symmetric Grothendieck-Witt theory satisfy Nisnevich descent, and…

K-Theory and Homology · Mathematics 2025-01-27 Baptiste Calmès , Yonatan Harpaz , Denis Nardin

We develop a theory of motivic spectra in a broad generality; in particular $\mathbb{A}^1$-homotopy invariance is not assumed. As an application, we prove that $K$-theory of schemes is a universal Zariski sheaf of spectra which is equipped…

Algebraic Geometry · Mathematics 2025-04-18 Toni Annala , Ryomei Iwasa

We formulate and prove a Conner-Floyd isomorphism for the algebraic K-theory of arbitrary qcqs derived schemes. To that end, we study a stable $\infty$-category of non-$\mathbb A^1$-invariant motivic spectra, which turns out to be…

Algebraic Geometry · Mathematics 2024-02-15 Toni Annala , Marc Hoyois , Ryomei Iwasa

We consider the problem of smoothing algebraic cycles with rational coefficients on smooth projective complex varieties up to homological equivalence. We show that a solution to this problem would be incompatible with the validity of the…

Algebraic Geometry · Mathematics 2024-10-22 Olivier Benoist , Claire Voisin

Let $\sigma$ be the involution of the Roe algebra $\Roe{\RR}$ which is induced from the reflection $\RR\to\RR; x\mapsto -x$. A graded Fredholm module over a separable $C^*$-algebra $A$ gives rise to a homomorphism…

K-Theory and Homology · Mathematics 2010-03-10 Robert Yuncken

In order to have cohomological operations for de Rham p-adic cohomology with coefficients as manageable as possible, the main purpose of this paper is to solve intrinsically and from a cohomological point of view the lifting problem of…

Algebraic Geometry · Mathematics 2010-09-17 Alberto Dario Arabia , Zoghman Mebkhout

Let $R$ be the homogeneous coordinate ring of a smooth projective variety $X$ over a field $\k$ of characteristic~0. We calculate the $K$-theory of $R$ in terms of the geometry of the projective embedding of $X$. In particular, if $X$ is a…

K-Theory and Homology · Mathematics 2010-02-22 Guillermo Cortiñas , Christian Haesemeyer , Mark E. Walker , Charles A. Weibel

For a smooth quasi-projective scheme $X$ over a field $k$ with an action of a reductive group, we establish a spectral sequence connecting the equivariant and the ordinary higher Chow groups of $X$. For $X$ smooth and projective, we show…

Algebraic Geometry · Mathematics 2016-12-01 Amalendu Krishna

We generalize several basic facts about the motivic sphere spectrum in $\mathbb A^1$-homotopy theory to the category $\mathrm{MS}$ of non-$\mathbb A^1$-invariant motivic spectra over a derived scheme. On the one hand, we show that all the…

Algebraic Geometry · Mathematics 2024-10-23 Marc Hoyois

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 compute the generalized slices (as defined by Spitzweck-{\O}stv{\ae}r) of the motivic spectrum KO (representing hermitian K-theory) in terms of motivic cohomology and (a version of) generalized motivic cohomology, obtaining good…

K-Theory and Homology · Mathematics 2017-11-21 Tom Bachmann