scholarly journals Which rational double points occur on del Pezzo surfaces?

2021 ◽  
Vol Volume 5 ◽  
Author(s):  
Claudia Stadlmayr
Keyword(s):  
Positive Characteristic ◽  
Del Pezzo Surfaces ◽  
Closed Field ◽  
Arbitrary Degree ◽  
Algebraically Closed Field ◽  
Double Points ◽  
Arbitrary Characteristic ◽  
Classical Work ◽  
Del Pezzo

We determine all configurations of rational double points that occur on RDP del Pezzo surfaces of arbitrary degree and Picard rank over an algebraically closed field $k$ of arbitrary characteristic ${\rm char}(k)=p \geq 0$, generalizing classical work of Du Val to positive characteristic. Moreover, we give simplified equations for all RDP del Pezzo surfaces of degree $1$ containing non-taut rational double points.

scholarly journals GENERAL HYPERPLANE SECTIONS OF THREEFOLDS IN POSITIVE CHARACTERISTIC

2018 ◽  
Vol 19 (2) ◽  
pp. 647-661 ◽  
Author(s):  
Kenta Sato ◽  
Shunsuke Takagi
Keyword(s):  
Projective Variety ◽  
Positive Characteristic ◽  
Hyperplane Section ◽  
Three Dimensional ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
Double Points ◽  
Canonical Singularities ◽  
Hyperplane Sections

In this paper, we study the singularities of a general hyperplane section $H$ of a three-dimensional quasi-projective variety $X$ over an algebraically closed field of characteristic $p>0$. We prove that if $X$ has only canonical singularities, then $H$ has only rational double points. We also prove, under the assumption that $p>5$, that if $X$ has only klt singularities, then so does $H$.

scholarly journals On log del Pezzo surfaces in large characteristic

2017 ◽  
Vol 153 (4) ◽  
pp. 820-850 ◽  
Author(s):  
Paolo Cascini ◽  
Hiromu Tanaka ◽  
Jakub Witaszek
Keyword(s):  
Characteristic Zero ◽  
Pezzo Surface ◽  
Del Pezzo Surfaces ◽  
Closed Field ◽  
Vanishing Theorem ◽  
Del Pezzo Surface ◽  
Algebraically Closed Field ◽  
Del Pezzo ◽  
Log Del Pezzo Surfaces

We show that any Kawamata log terminal del Pezzo surface over an algebraically closed field of large characteristic is globally $F$-regular or it admits a log resolution which lifts to characteristic zero. As a consequence, we prove the Kawamata–Viehweg vanishing theorem for klt del Pezzo surfaces of large characteristic.

scholarly journals Formal orbifolds and orbifold bundles in positive characteristic

2019 ◽  
Vol 30 (12) ◽  
pp. 1950067
Author(s):  
Manish Kumar ◽  
A. J. Parameswaran
Keyword(s):  
Fundamental Group ◽  
Characteristic Zero ◽  
Vector Bundles ◽  
Positive Characteristic ◽  
Closed Field ◽  
Fundamental Groups ◽  
Projective Curve ◽  
Smooth Projective Curve ◽  
Algebraically Closed Field ◽  
Arbitrary Characteristic

We define formal orbifolds over an algebraically closed field of arbitrary characteristic as curves together with some branch data. Their étale coverings and their fundamental groups are also defined. These fundamental groups approximate the fundamental group of an appropriate affine curve. We also define vector bundles on these objects and the category of orbifold bundles on any smooth projective curve. Analogues of various statements about vector bundles which are true in characteristic zero are also proved. Some of these are positive characteristic avatars of notions which appear in the second author’s work [A. J. Parmeswaran, Parabolic coverings I: Case of curves, J. Ramanujam Math. Soc. 25(3) (2010) 233–251.] in characteristic zero.

scholarly journals Automorphisms of cubic surfaces in positive characteristic

2019 ◽  
Vol 83 (3) ◽  
pp. 15-92
Author(s):  
Игорь Владимирович Долгачев ◽  
Igor Vladimirovich Dolgachev ◽  
Alexander Duncan ◽  
Alexander Duncan
Keyword(s):  
Isomorphism Class ◽  
Normal Forms ◽  
Positive Characteristic ◽  
Automorphism Groups ◽  
Del Pezzo Surfaces ◽  
Closed Field ◽  
Intermediate Step ◽  
Cubic Surface ◽  
Cubic Surfaces ◽  
Del Pezzo

We classify all possible automorphism groups of smooth cubic surfaces over an algebraically closed field of arbitrary characteristic. As an intermediate step we also classify automorphism groups of quartic del Pezzo surfaces. We show that the moduli space of smooth cubic surfaces is rational in every characteristic, determine the dimensions of the strata admitting each possible isomorphism class of automorphism group, and find explicit normal forms in each case. Finally, we completely characterize when a smooth cubic surface in positive characteristic, together with a group action, can be lifted to characteristic zero. Bibliography: 29 titles.

scholarly journals Variation of stable birational types in positive characteristic

2020 ◽  
Vol Volume 3 ◽  
Author(s):  
Stefan Schreieder
Keyword(s):  
Characteristic Zero ◽  
Positive Characteristic ◽  
Closed Field ◽  
Final Version ◽  
Algebraically Closed Field ◽  
Arbitrary Characteristic

Let k be an uncountable algebraically closed field and let Y be a smooth projective k-variety which does not admit a decomposition of the diagonal. We prove that Y is not stably birational to a very general hypersurface of any given degree and dimension. We use this to study the variation of the stable birational types of Fano hypersurfaces over fields of arbitrary characteristic. This had been initiated by Shinder, whose method works in characteristic zero. Comment: 14 pages; final version, published in EPIGA

scholarly journals Polarizations on abelian varieties

2002 ◽  
Vol 133 (2) ◽  
pp. 223-233 ◽  
Author(s):  
A. SILVERBERG ◽  
YU. G. ZARHIN
Keyword(s):  
Abelian Variety ◽  
Finite Fields ◽  
Positive Characteristic ◽  
Abelian Varieties ◽  
Number Fields ◽  
General Context ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
Arbitrary Characteristic

Every isogeny class over an algebraically closed field contains a principally polarized abelian variety ([10, corollary 1 to theorem 4 in section 23]). Howe ([3]; see also [4]) gave examples of isogeny classes of abelian varieties over finite fields with no principal polarizations (but not with the degrees of all the polarizations divisible by a given non-zero integer, as in Theorem 1·1 below). In [17] we obtained, for all odd primes [lscr ], isogeny classes of abelian varieties in positive characteristic, all of whose polarizations have degree divisible by [lscr ]2. We gave results in the more general context of invertible sheaves; see also Theorems 6·1 and 5·2 below. Our results gave the first examples for which all the polarizations of the abelian varieties in an isogeny class have degree divisible by a given prime. Inspired by our results in [17], Howe [5] recently obtained, for all odd primes [lscr ], examples of isogeny classes of abelian varieties over fields of arbitrary characteristic different from [lscr ] (including number fields), all of whose polarizations have degree divisible by [lscr ]2.

On the equations for universal torsors over del Pezzo surfaces

2009 ◽  
Vol 9 (1) ◽  
pp. 203-223 ◽  
Author(s):  
Vera V. Serganova ◽  
Alexei. N. Skorobogatov
Keyword(s):  
Homogeneous Space ◽  
Del Pezzo Surfaces ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
Del Pezzo

AbstractWe describe equations of the universal torsors over del Pezzo surfaces of degrees from 2 to 5 over an algebraically closed field in terms of the equations of the corresponding homogeneous space G/P. We also give a generalization for fields that are not algebraically closed.

scholarly journals Classification of one-dimensional superattracting germs in positive characteristic

2014 ◽  
Vol 35 (7) ◽  
pp. 2242-2268 ◽  
Author(s):  
MATTEO RUGGIERO
Keyword(s):  
Positive Characteristic ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
One Dimensional ◽  
Higher Dimensional ◽  
Dimensional Version

We give a classification of superattracting germs in dimension $1$ over a complete normed algebraically closed field $\mathbb{K}$ of positive characteristic up to conjugacy. In particular, we show that formal and analytic classifications coincide for these germs. We also give a higher-dimensional version of some of these results.

scholarly journals A remark on the Grothendieck-Lefschetz theorem about the Picard group

1978 ◽  
Vol 71 ◽  
pp. 169-179 ◽  
Author(s):  
Lucian Bădescu
Keyword(s):  
Algebraic Variety ◽  
Picard Group ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
Arbitrary Characteristic ◽  
Lefschetz Theorem

Let K be an algebraically closed field of arbitrary characteristic. The term “variety” always means here an irreducible algebraic variety over K. The notations and the terminology are borrowed in general from EGA [4].

Sign in / Sign up

Export Citation Format

Share Document