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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 prove that an algebraic stack with affine stabilizers over an arbitrary base is \'etale-locally a quotient stack around any point with a linearly reductive stabilizer. This generalizes earlier work by the authors of this article (stacks…

Algebraic Geometry · Mathematics 2025-04-07 Jarod Alper , Jack Hall , David Rydh

The purpose of this paper is to lay the foundations of a theory of invariants in \'etale cohomology for smooth Artin stacks. We compute the invariants in the case of the stack of elliptic curves, and we use the theory we developed to get…

Algebraic Geometry · Mathematics 2017-07-05 Roberto Pirisi

Over any field of characteristic not 2, we establish a 2-term resolution of the $\eta$-periodic, 2-local motivic sphere spectrum by shifts of the connective 2-local Witt K-theory spectrum. This is curiously similar to the resolution of the…

K-Theory and Homology · Mathematics 2021-05-05 Tom Bachmann , Michael J. Hopkins

Let $k$ be an algebraically closed field of exponential characteristic $p$. Given any prime $\ell\neq p$, we construct a stable \'etale realization functor $$\underline{\text{\'Et}}_{\ell}:\text{Spt}(k)\rightarrow…

Algebraic Geometry · Mathematics 2017-08-25 Masoud Zargar

We present an algorithm for explicitly computing the number of generators of the stable cohomology algebra of any rationally smooth partial toroidal compactification of ${\mathcal A}_g$, satisfying certain additivity and finiteness…

Algebraic Geometry · Mathematics 2017-02-22 Samuel Grushevsky , Klaus Hulek , Orsola Tommasi

For every adic space $Z$ we construct a site $Z_t$, the tame site of $Z$. For a scheme $X$ over a base scheme $S$ we obtain a tame site by associating with $X/S$ an adic space $\textit{Spa}(X,S)$ and considering the tame site…

Algebraic Geometry · Mathematics 2021-06-02 Katharina Hübner

In the framework of Atiyah's axioms of topological quantum field theory with unitarity, we give a direct proof of the fact that symmetry protected topological (SPT) phases without Hall effects are classified by cobordism invariants. We…

High Energy Physics - Theory · Physics 2019-06-18 Kazuya Yonekura

Let k be an infinite perfect field. We provide a general criterion for a spectrum in the stable homotopy category over k to be effective, i.e. to be in the localizing subcategory generated by the suspension spectra of smooth schemes. As a…

K-Theory and Homology · Mathematics 2018-07-09 Tom Bachmann , Jean Fasel

We prove an effective stabilization result for the sheaf cohomology groups of line bundles on flag varieties parametrizing complete flags in k^n, as well as for the sheaf cohomology groups of polynomial functors applied to the cotangent…

Algebraic Geometry · Mathematics 2026-02-10 Claudiu Raicu , Keller VandeBogert

We extend the stable motivic homotopy category of Voevodsky to the class of scalloped algebraic stacks, and show that it admits the formalism of Grothendieck's six operations. Objects in this category represent generalized cohomology…

Algebraic Geometry · Mathematics 2024-10-10 Adeel A. Khan , Charanya Ravi

We give a new definition of the derived category of constructible $\ell$-adic sheaves on a scheme, which is as simple as the geometric intuition behind them. Moreover, we define a refined fundamental group of schemes, which is large enough…

Algebraic Geometry · Mathematics 2014-12-18 Bhargav Bhatt , Peter Scholze

This paper has two main goals. First, we prove nonabelian refinements of basechange theorems in \'etale cohomology (i.e., prove analogues of the classical statements for sheaves of spaces). Second, we apply these theorems to prove a number…

Algebraic Geometry · Mathematics 2024-06-07 Peter J. Haine , Tim Holzschuh , Sebastian Wolf

We present a geometric construction of push-forward maps along projective morphisms for cohomology theories representable in the stable motivic homotopy category assuming that the element corresponding to the stable Hopf map is inverted in…

Algebraic Geometry · Mathematics 2015-10-26 Alexey Ananyevskiy

We adapt algorithms for resolving the singularities of complex algebraic varieties to prove that the natural map of homology theories from complex bordism to the bordism theory of complex derived orbifolds splits. In equivariant stable…

Algebraic Topology · Mathematics 2025-04-25 Mohammed Abouzaid , Shaoyun Bai

We study the category pro-SSet of pro-simplicial sets, which arises in etale homotopy theory, shape theory, and pro-finite completion. We establish a model structure on pro-SSet so that it is possible to do homotopy theory in this category.…

Algebraic Topology · Mathematics 2007-05-23 Daniel C. Isaksen

Grothendieck duality theory assigns to essentially-finite-type maps f of noetherian schemes a pseudofunctor f^\times right-adjoint to Rf_*, and a pseudofunctor f^! agreeing with f^\times when f is proper, but equal to the usual inverse…

Algebraic Geometry · Mathematics 2019-02-20 Srikanth B. Iyengar , Joseph Lipman , Amnon Neeman

We study the locus of smooth hypersurfaces inside the Hilbert scheme of a smooth projective complex variety. In the spirit of scanning, we construct a map to a continuous section space of a projective bundle, and show that it induces an…

Algebraic Geometry · Mathematics 2026-03-11 Alexis Aumonier

The purpose of this article is to define the topological realization of a simplicial presheaf and to prove (under appropriate conditions) that it is homotopy-invariant under Illusie weak equivalence. In particular this applies to the site…

q-alg · Mathematics 2008-02-03 Carlos Simpson

We show that the spectral radius for the action of a self map $f$ of a smooth projective variety (over an arbitrary base field) on its $\ell$-adic cohomology is achieved on the $f^*$-stable sub-algebra generated by any ample class. This…

Algebraic Geometry · Mathematics 2021-06-25 K. V. Shuddhodan