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We give a different proof of Nuer's result on the exsistence of stable sheaves on Enriques surfaces.

Algebraic Geometry · Mathematics 2015-12-02 Kota Yoshioka

We establish Noether's inequality for surfaces of general type in positive characteristic.Then we extend Enriques' and Horikawa's classification of surfaces on the Noether line, the so-called Horikawa surfaces. We construct examples for all…

Algebraic Geometry · Mathematics 2008-09-17 Christian Liedtke

We give a number of examples of pairs of non-compact surfaces which are isoscattering, and which are exceptionally simple in one or more senses. We give examples which are of small genus with a small number of ends, and also examles which…

Differential Geometry · Mathematics 2007-05-23 Robert Brooks , Orit Davidovich

For an isolated hypersurface singularity which is neither simple nor simple elliptic, it is shown that there exists a distinguished basis of vanishing cycles which contains two basis elements with an arbitrary intersection number. This…

Algebraic Geometry · Mathematics 2017-06-13 Wolfgang Ebeling

We define the notion of an exceptional manifold to be a flat Riemannian manifold with boundary which supports a positive harmonic function satisfying simultaneously a zero Dirichlet condition and a constant (nonzero) Neumann condtion at the…

Mathematical Physics · Physics 2010-01-11 Frédéric Hélein , Laurent Hauswirth , Frank Pacard

We give a complete classification of finite groups acting symplectically on supersingular K3 surfaces of Artin invariant one. Using work of Dolgachev and Keum, this provides the full classification of tame finite symplectic automorphism…

Algebraic Geometry · Mathematics 2026-05-04 Hisanori Ohashi , Matthias Schütt

We construct the first exotic $\mathbb C \mathbb P^2 \# 4 \overline{\mathbb C \mathbb P^2}$ by means of rational blowdowns. Similarly, we construct the first exotic $3\mathbb C \mathbb P^2 \# b^- \overline{\mathbb C \mathbb P^2}$ for…

Algebraic Geometry · Mathematics 2022-11-24 Javier Reyes , Giancarlo Urzúa

Barth and Peters showed that a general complex Enriques surface has exactly 527 isomorphism classes of elliptic fibrations. We show that every Enriques surface has precisely 527 isomorphism classes of elliptic fibrations when counted with…

Algebraic Geometry · Mathematics 2024-08-02 Simon Brandhorst , Víctor González-Alonso

Given a hypersurface in a complex projective space, we prove that the multidegrees of its toric polar map agree, up to sign, with the coefficients of the Chern-Schwartz-MacPherson class of a distinguished open set, namely the complement of…

Algebraic Geometry · Mathematics 2023-05-03 Thiago Fassarella , Nivaldo Medeiros , Rodrigo Salomão

We show that if the Segre varieties of a strictly pseudoconvex hypersurface in $\mathbb{C}^2$ are extremal discs for the Kobayashi metric, then that hypersurface has to be locally spherical. In particular, this gives yet another…

Complex Variables · Mathematics 2020-09-15 Florian Bertrand , Giuseppe Della Sala , Bernhard Lamel

We first introduce global arithmetic cohomology groups for quasi-coherent sheaves on arithmetic varieties, adopting an adelic approach. Then, we establish fundamental properties, such as topological duality and inductive long exact…

Algebraic Geometry · Mathematics 2015-07-23 K. Sugahara , L. Weng

Let X be a smooth double cover of a geometrically ruled surface defined over a separably closed field of characteristic different from 2. The main result of this paper is a finite presentation of the 2-torsion in the Brauer group of X with…

Number Theory · Mathematics 2015-12-18 Brendan Creutz , Bianca Viray

We investigate surface singularities defined by weighted-L\^e-Yomdin polynomials, with a particular focus on a specific subclass that we refer to as Newton weighted-L\^e-Yomdin polynomials. In particular, using polynomials in this subclass,…

Algebraic Geometry · Mathematics 2025-11-11 Christophe Eyral , Masaharu Ishikawa , Mutsuo Oka

This paper develops families of complex Enriques surfaces whose Brauer groups pull back identically to zero on the covering K3 surfaces. Our methods rely on isogenies with Kummer surfaces of product type. We offer both lattice theoretic and…

Algebraic Geometry · Mathematics 2011-02-11 Alice Garbagnati , Matthias Schuett

We investigate geometric properties of surfaces given by certain formulae. In particular, we calculate the singular curvature and the limiting normal curvature of such surfaces along the set of singular points consisting of singular points…

Differential Geometry · Mathematics 2020-03-25 Yoshiki Matsushita , Takuya Nakashima , Keisuke Teramoto

In this article, we consider surfaces in the 3-dimensional Euclidean space E3 without parabolic points which are of finite II-type, that is, they are of finite type, in the sense of B.-Y. Chen, corresponding to the second fundamental form.…

General Mathematics · Mathematics 2019-02-25 Hassan Al-Zoubi , Amer Dababneh , Waseem Mashaleh , Nancy Ramahi

We consider closed orientable hypersurfaces in a wide class of warped product manifolds, which include space forms, deSitter-Schwarzschild and Reissner-Nordstr\"{o}m manifolds. By using a new integral formula or Brendle's Heintze-Karcher…

Differential Geometry · Mathematics 2019-02-14 Shanze Gao , Hui Ma

Hierarchies of evolution equations of pseudo-spherical type are introduced, generalizing the notion of a single equation describing pseudo-spherical surfaces due to S.S. Chern and K. Tenenblat, and providing a connection between…

Exactly Solvable and Integrable Systems · Physics 2007-05-23 Enrique G. Reyes

In this paper we classify certain special ruled surfaces in $\R^3$ under the general theorem of characterization of constant angle surfaces. We study the tangent developable and conical surfaces from the point of view the constant angle…

Differential Geometry · Mathematics 2009-04-10 Ana-Irina Nistor

We prove the rationality of the coarse moduli spaces of Coble surfaces and of nodal Enriques surfaces over the field of complex numbers.

Algebraic Geometry · Mathematics 2015-06-04 Igor Dolgachev , Shigeyuki Kondo