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We prove a motivic enhancement of the classical Picard--Lefschetz formula. Our proof is completely motivic, and yields a description of the motivic nearby cycles at a quasi-homogeneous singularity, as well as its monodromy, in terms of an…

Algebraic Geometry · Mathematics 2025-10-15 Ran Azouri , Emil Jacobsen

Let $S$ be a smooth projective surface over a field. We introduce the notion of integral decomposability and, respectively, the opposite notion of integral indecomposability, of the transcendental motive $M^2_{\rm tr}(S)$. If the…

Algebraic Geometry · Mathematics 2018-04-20 Vladimir Guletskii

We introduce a tower of localizing subcategories in Voevodsky's big (closed under infinite coproducts) triangulated category of motives. We show that the tower induces an interesting finite filtration on the motivic cohomology groups of…

Algebraic Geometry · Mathematics 2016-10-11 Pablo Pelaez

The goal of this paper is to study non-$\mathbb{A}^1$-invariant motivic cohomology, recently defined by Elmanto, Morrow, and the first-named author, for smooth schemes over possibly non-discrete valuation rings. We establish that the cycle…

Algebraic Geometry · Mathematics 2025-06-12 Tess Bouis , Arnab Kundu

Let $\mathfrak{Var}_k^G$ denote the category of pairs $(X,\sigma)$, where $X$ is a variety over $k$ and $\sigma$ is a group action on $X$. We define the Grothendieck ring for varieties with group actions as the free abelian group of…

Algebraic Geometry · Mathematics 2011-03-14 Justin Mazur

Let X be a smooth projective variety over a field k. For k separably closed, we prove that the subgroup of unramified classes in the Milnor K-group $K^M_i(k(X))$ of the function field of X is contained in the subgroup of n-divisible…

Algebraic Geometry · Mathematics 2026-05-22 Jean-Louis Colliot-Thélène , Stefan Schreieder

This paper deals with cyclic covers of a large family of rational normal surfaces that can also be described as quotients of a product, where the factors are cyclic covers of algebraic curves. We use a generalization of Esnault-Viehweg…

Algebraic Geometry · Mathematics 2023-04-20 Enrique Artal Bartolo , José Ignacio Cogolludo-Agustín , Jorge Martín-Morales

In this paper we construct new indecomposable motivic cycles in the group $H^3_{\mathcal M}(X,{\mathbb Q}(2))$ where X is a degree 2 K3 surface. This generalizes our construction in [Sre22] for Kummer surfaces of Abelian surfaces as well as…

Algebraic Geometry · Mathematics 2024-11-12 Ramesh Sreekantan

In this thesis we give two applications of Ayoub's motivic nearby cycles functor: First we give a generalization of Grothendieck's classical local monodromy theorem. In the classical setup we show that the inertia group acts…

Algebraic Geometry · Mathematics 2023-05-08 Benedikt Preis

We show that the Grothendieck period conjecture holds for the Kummer surface associated with the square of a CM elliptic curve. This means that the period isomorphism is dense in the torsor of motivic periods. In other words, the…

Algebraic Geometry · Mathematics 2026-05-19 Daiki Kawabe

We study the motivic Serre invariant of a smoothly bounded algebraic or rigid variety $X$ over a complete discretely valued field $K$ with perfect residue field $k$. If $K$ has characteristic zero, we extend the definition to arbitrary…

Algebraic Geometry · Mathematics 2008-09-26 Johannes Nicaise

Using iterated vanishing cycles and convolution, we prove a motivic version of a conjecture of Steenbrink concerning the spectrum of hypersurface singularities

Algebraic Geometry · Mathematics 2007-12-05 G. Guibert , F. Loeser , M. Merle

For an infinity of number rings we express stable motivic invariants in terms of topological data determined by the complex numbers, the real numbers, and finite fields. We use this to extend Morel's identification of the endomorphism ring…

K-Theory and Homology · Mathematics 2023-06-22 Tom Bachmann , Paul Arne Østvær

We study cyclic covering morphisms from $\bar{M}_{0,n}$ to moduli spaces of unpointed stable curves of positive genus or compactified moduli spaces of principally polarized abelian varieties. Our main application is a construction of new…

Algebraic Geometry · Mathematics 2011-05-16 Maksym Fedorchuk

The main aim of this paper is to show that a cyclic cover of $\mathbb{P}^n$ branched along a very general divisor of degree $d$ is not stably rational provided that $n \ge 3$ and $d \ge n+1$. This generalizes the result of…

Algebraic Geometry · Mathematics 2019-07-10 Takuzo Okada

This paper proves two theorems (1) Let $k$ be an algebraically closed field of characteristic $p>0$. I prove (Theorem 2.1.1) that if, $p > 13$ or $p = 11$, then the isomorphism class of any supersingular elliptic curve is a zero divisor in…

Algebraic Geometry · Mathematics 2026-05-12 Kirti Joshi

We exhibit an example of covering surface of C*, arising from analytical continuation of a holomorphic germ and failing to be a topological covering, due to singular points and regular ones being projected over the same slits in C*.

Complex Variables · Mathematics 2008-07-11 Claudio Meneghini

This paper introduces the trivial fiber topology on schemes. For one-dimensional base schemes, we use it to describe fibrant replacements in the stable motivic homotopy category and motivic infinite loop spaces. We also extend the…

Algebraic Geometry · Mathematics 2023-01-16 A. Druzhinin , Håkon Kolderup , Paul Arne Østvær

We construct motivic cohomology cycles in the group $H^3_{\mathcal M}(Z,{\mathbb Q}(2))$ where $Z$ is a K3 surface obtained as a double cover of a del Pezzo surface $X$ branched at a curve in $|-2K_X|$. The construction uses (-1) curves on…

Algebraic Geometry · Mathematics 2024-11-07 Ramesh Sreekantan

We show that the cellular objects in the module category over a motivic E infinity ring spectrum E can be described as the module category over a graded topological spectrum if E is strongly periodizable in our language. A similar statement…

Algebraic Geometry · Mathematics 2009-08-04 Markus Spitzweck