نتایج جستجو برای: سنجنده severi

تعداد نتایج: 2057  

2008
Matthias Schütt

We determine all complex K3 surfaces with Picard rank 20 over Q. Here the NéronSeveri group has rank 20 and is generated by divisors which are defined over Q. Our proof uses modularity, the Artin-Tate conjecture and class group theory. With different techniques, the result has been established by Elkies to show that Mordell-Weil rank 18 over Q is impossible for an elliptic K3 surface. We also a...

2007
Jean-Benôıt Bost

Instances of such “arithmetic 1-extensions” naturally arise in arithmetic geometry and in geometry of numbers. In this talk we discuss an arithmetic analog of the Enriques-Severi-Zariski Lemma in classical algebraic geometry: namely, if X is a projective integral scheme over SpecZ and if the class of EQ in the classical extension group Ext1XQ(EQ, FQ) does not vanish, then for “many” points P in...

Journal: :Cubo 2022

Let \({\mathscr{V}}\) be a variety related to the second row of Freudenthal-Tits Magic square in \(N\)-dimensional projective space over an arbitrary field. We show that there exist \(M\leq N\) quadrics intersecting precisely if and only exists subspace dimension \(N-M\) secant disjoint from Severi variety. present some examples such subspaces relatively large dimension. In particular, real num...

Journal: :Rendiconti Del Circolo Matematico Di Palermo 2023

We investigate a strong version of the integral Tate conjecture for 1-cycles on product curve and surface over finite field, under assumption that is geometrically $$CH_0$$ -trivial. By this we mean any algebraically closed field extension, degree map zero-dimensional Chow group an isomorphism. This applies to Enriques surfaces. When Néron-Severi has no torsion, recover earlier results A. Pirut...

Journal: :International Mathematics Research Notices 2021

Abstract In this note, we investigate some regularity aspects for solutions of degenerate complex Monge–Ampère equations (DCMAE) on singular spaces. First, study the Dirichlet problem DCMAE Stein spaces, showing a general continuity result. A consequence our results is that Kähler–Einstein potentials are continuous at isolated singularities. Next, establish global to when reference class belong...

2005
B. Calmès V. Petrov N. Semenov K. Zainoulline May

Let G be an adjoint simple algebraic group of inner type. We express the Chow motive (with integral coefficients) of some anisotropic projective G-homogeneous varieties in terms of motives of simpler G-homogeneous varieties, namely, those that correspond to maximal parabolic subgroups of G. We decompose the motive of a generalized Severi-Brauer variety SB2(A), where A is a division algebra of d...

2009
Sylvain Brochard

We prove some finiteness theorems for the Picard functor of an algebraic stack, in the spirit of SGA6, exp. XII and XIII. In particular, we give a stacky version of Raynaud’s relative representability theorem, we give sufficient conditions for the existence of the torsion component of the Picard functor, and for the finite generation of the Néron-Severi groups or of the Picard group itself. We ...

2017
Anthony Várilly-Alvarado

For a prime p, we study subgroups of order p of the Brauer group Br(S) of a general complex polarized K3 surface of degree 2d, generalizing earlier work of van Geemen. These groups correspond to sublattices of index p of the transcendental lattice TS of S; we classify these lattices up to isomorphism using Nikulin’s discriminant form technique. We then study geometric realizations of p-torsion ...

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