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We compute the characteristic cycle of a rank one sheaf on a smooth surface over a perfect field of positive characteristic. We construct a canonical lifting on the cotangent bundle of Kato's logarithmic characteristic cycle using…

Algebraic Geometry · Mathematics 2017-12-27 Yuri Yatagawa

We define the characteristic cycle of an etale sheaf as a cycle on the cotangent bundle of a smooth variety in positive characteristic using the singular support recently defined by Beilinson. We prove a formula a la Milnor for the total…

Algebraic Geometry · Mathematics 2018-01-11 Takeshi Saito

We compute the singular support and the characteristic cycle of a rank 1 sheaf on a smooth variety in codimension 2 using ramification theory, when the ramification of the sheaf is clean. We develop a general theory, called the partially…

Algebraic Geometry · Mathematics 2022-06-08 Yuri Yatagawa

For a smooth morphism $f: X \longrightarrow \Sigma$ of real analytic manifolds and an $\mathbb{R}$-constructible sheaf $F$ on $X$ satisfying some condition, we define a family of Lagrangian cycles parameterized by $\Sigma$ that we call the…

Algebraic Geometry · Mathematics 2026-03-17 Ren Fernandes , Kazuki Kudomi , Kiyoshi Takeuchi

The refined Swan conductor is defined by K.\ Kato \cite{KK2}, and generalized by T.\ Saito \cite{wild}. In this part, we consider some smooth $l$-adic \'{e}tale sheaves of rank $p$ such that we can be define the $rsw$ following T.\ Saito,…

Number Theory · Mathematics 2011-03-08 Qizhi Zhang

We define the characteristic cycle of a constructible sheaf on a smooth surface in the cotangent bundle. We prove that the intersection number with the 0-section equals the Euler number and that the total dimension of vanishing cycles at an…

Algebraic Geometry · Mathematics 2015-10-14 Takeshi Saito

This article is devoted to studying the ramification of Galois torsors and of $\ell$-adic sheaves in characteristic $p>0$ (with $\ell\not=p$). Let $k$ be a perfect field of characteristic $p>0$, $X$ be a smooth, separated and quasi-compact…

Algebraic Geometry · Mathematics 2011-10-25 Ahmed Abbes , Takeshi Saito

We study some properties of the characteristic cycle of a constructible complex on a smooth variety over a perfect field, push-forward and product.

Algebraic Geometry · Mathematics 2016-07-14 Takeshi Saito

Given a constructible sheaf $F$ on a complex manifold, Kashiwara-Schapira defined the notion of singular support and characteristic cycle of $F$. On the other hand for a Zariski constructible \'{e}tale sheaf $F$ on an algebraic variety $X$,…

Algebraic Geometry · Mathematics 2023-12-18 Ankit Rai

We define a numerical invariant, the differential Swan conductor, for certain differential modules on a rigid analytic annulus over a p-adic field. This gives a definition of a conductor for p-adic Galois representations with finite local…

Number Theory · Mathematics 2007-09-18 Kiran S. Kedlaya

Let $X$ be a smooth variety over a finite field $\mathbb{F}_q$. Let $\ell$ be a rational prime number invertible in $\mathbb{F}_q$. For an $\ell$-adic sheaf $\mathcal{F}$ on $X$, we construct a cycle supported on the singular support of…

Algebraic Geometry · Mathematics 2026-04-06 Daichi Takeuchi

We define the characteristic cycle of a locally constant \'etale sheaf on a smooth variety in positive characteristic ramified along boundary as a cycle in the cotangent bundle of the variety, at least on a neighborhood of the generic point…

Algebraic Geometry · Mathematics 2020-03-24 Takeshi Saito

Let $k$ be a field of arbitrary characteristic. Let $S$ be a singular surface defined over $k$ with multiple rational curve singularities and suppose that the Chow group of zero cycles of its normalisation $\tilde{S}$ is finite dimensional.…

Algebraic Geometry · Mathematics 2007-05-23 G V Ravindra

We study zero-cycles in families of rationally connected varieties. We show that for a smooth projective scheme over a henselian discrete valuation ring the restriction of relative zero cycles to the special fiber induces an isomorphism on…

Algebraic Geometry · Mathematics 2024-07-11 Morten Lüders

An $\ell$-adic GKZ hypergeometric sheaf is defined analogously to a GKZ hypergeometric $\mathcal{D}$-module. We introduce an algorithm of computing the characteristic cycle of an $\ell$-adic GKZ hypergeometric sheaf of certain type. Our…

Algebraic Geometry · Mathematics 2024-07-24 Peijiang Liu

For a character of the absolute Galois group of a complete discrete valuation field, we define a lifting of the refined Swan conductor, using higher dimensional class field theory.

Algebraic Geometry · Mathematics 2020-03-24 Kazuya Kato , Isabel Leal , Takeshi Saito

Let $R$ be a complete discrete valuation ring with residue characteristic $p>0$. In this note we give an example of a Galois cover $f:Y\to X$ between flat and normal formal $R$-schemes of finite type which is \'etale above the generic fibre…

Algebraic Geometry · Mathematics 2007-05-23 Saidi Mohamed

We study the compatibility with proper push-forward of the characteristic cycles of a constructible complex on a smooth variety over a perfect field.

Algebraic Geometry · Mathematics 2020-03-24 Takeshi Saito

Let $k$ be a perfect field of characteristic $p$, let $f_i:X_i\to\mathbb A_k^1$ $(i=1,2)$ be two $k$-morphism of finite type, and let $f:X_1\times_k X_2\to \mathbb A_k^1$ be the morphism defined by $f(z_1,z_2)=f_1(z_1)+f_2(z_2)$. For each…

Algebraic Geometry · Mathematics 2013-12-31 Lei Fu

Relying on the formalism developed by Alexander Beilinson and Takeshi Saito, we compute the characteristic cycle of an external symmetric power of a tame \'etale sheaf on a curve. This generalizes a result of G\'erard Laumon in…

Algebraic Geometry · Mathematics 2026-05-20 Fabrice Orgogozo , Joël Riou
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