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In this article we study forms of the Segre cubic over non-algebraically closed fields, their automorphism groups and equivariant birational rigidity. In particular, we show that all forms of the Segre cubic are cubic hypersurfaces and all…

Algebraic Geometry · Mathematics 2019-01-01 Artem Avilov

Using the Schwarzian derivative we construct a sequence $\left(P_{\ell}\right)_{\ell \geqslant 2}$ of meromorphic differentials on every non-flat oriented minimal surface in Euclidean $3$-space. The differentials…

Differential Geometry · Mathematics 2024-07-23 Thomas Mettler , Lukas Poerschke

After a few results on curves, we characterize the smallest nonempty Terracini loci of Veronese and Segre-Veronese varieties. For del Pezzo surfaces, we give a full description of the Terracini loci. Moreover, we present an algorithm to…

Algebraic Geometry · Mathematics 2025-04-30 Francesco Galuppi , Pierpaola Santarsiero , Douglas A. Torrance , Ettore Teixeira Turatti

In this paper, we will show that a vanishing generalized concurrence of a separable state can be seen as an algebraic variety called the Segre variety. This variety define a quadric space which gives a geometric picture of separable states.…

Quantum Physics · Physics 2016-08-16 Hoshang Heydari , Gunnar Björk

We investigate the structure of a variety of new Moishezon twistor spaces, by utilizing the pluri-half-anti-canonical map from the twistor spaces. Each of these twistor spaces is bimeromorphic to a double covering of a scroll of planes over…

Algebraic Geometry · Mathematics 2018-11-01 Nobuhiro Honda

We prove an identity of Segre classes for zero-schemes of compatible sections of two vector bundles. Applications include bounds on the number of equations needed to cut out a scheme with the same Segre class as a given subscheme of (for…

Algebraic Geometry · Mathematics 2016-10-18 Paolo Aluffi

We study admissible subcategories of derived categories of coherent sheaves on del Pezzo surfaces and rational elliptic surfaces. Using a relation between admissible subcategories and anticanonical divisors we prove the following results.…

Algebraic Geometry · Mathematics 2020-06-16 Dmitrii Pirozhkov

The Segre cubic and Castelnuovo-Richmond quartic are two projectively dual hypersurfaces in $\mathbb{P}^4$, with a long and rich history starting in the 19th century. We will explain how Kuznetsov's theory of homological projective duality…

Algebraic Geometry · Mathematics 2022-02-18 Thorsten Beckmann , Pieter Belmans

A minimal family of curves on an embedded surface is defined as a 1-dimensional family of rational curves of minimal degree, which cover the surface. We classify such minimal families using constructive methods. This allows us to compute…

Algebraic Geometry · Mathematics 2021-03-09 Niels Lubbes

This paper studies the dimension of secant varieties to Segre varieties. The problem is cast both in the setting of tensor algebra and in the setting of algebraic geometry. An inductive procedure is built around the ideas of successive…

Algebraic Geometry · Mathematics 2007-05-23 Hirotachi Abo , Giorgio Ottaviani , Chris Peterson

The Severi variety V_{n,d} of a smooth projective surface S is defined as the subvariety of the linear system |O_S(n)|, which parametrizes curves with d nodes. We show that, for a general surface S of degree k in P^3 and for all n>k-1,…

Algebraic Geometry · Mathematics 2007-05-23 L. Chiantini , C. Ciliberto

The equation determining whether a projective structure admits a connection in its given projective class that has skew-symmetric Ricci tensor is an overdetermined system of semi-linear partial differential equations which we call the…

Differential Geometry · Mathematics 2015-06-15 Matthew Randall

It is known that any Mori fiber space birational to a minimal smooth del Pezzo surface $S$ of degree $4$ is either a del Pezzo surface of degree $4$ itself, or a smooth cubic surface with a structure of a relatively minimal conic bundle. We…

Algebraic Geometry · Mathematics 2025-12-23 Constantin Shramov , Andrey Trepalin

We construct wonderful compactifications of the spaces of linear maps, and symmetric linear maps of a given rank as blow-ups of secant varieties of Segre and Veronese varieties. Furthermore, we investigate their birational geometry and…

Algebraic Geometry · Mathematics 2022-09-22 Alex Casarotti , Elsa Corniani , Alex Massarenti

We construct first examples of singular del Pezzo surfaces with Zariski dense exceptional sets in Manin's conjecture, varying in degrees $1, 2$ and $3$. The obstructions arise from accumulating quasi-\'etale covers. We classify all…

Algebraic Geometry · Mathematics 2025-03-05 Runxuan Gao

Classification of curves in a projective space occupies minds of many mathematicians. First step in doing so is classification of curves on a given surface. This brings us to consideration of the nonsingular Del Pezzo Surface in $P^4_k.$ We…

Algebraic Geometry · Mathematics 2007-05-23 Elena Drozd

We study Veronese and Segre morphisms between non-commutative projective spaces. We compute finite reduced Gr\"obner bases for their kernels, and we compare them with their analogues in the commutative case.

Quantum Algebra · Mathematics 2022-06-14 Francesca Arici , Francesco Galuppi , Tatiana Gateva-Ivanova

We classify morphisms from proper varieties to Brauer-Severi varieties, which generalizes the classical correspondence between morphisms to projective space and globally generated invertible sheaves. As an application, we study del Pezzo…

Algebraic Geometry · Mathematics 2017-02-10 Christian Liedtke

We study the algebraic Brauer classes on open del Pezzo surfaces of degree $4$. I.e., on the complements of geometrically irreducible hyperplane sections of del Pezzo surfaces of degree $4$. We show that the $2$-torsion part is generated by…

Algebraic Geometry · Mathematics 2019-01-14 Jörg Jahnel , Damaris Schindler

Iterated Segre mappings of real analytic generic submanifolds in complex space have been an essential tool in the study of holomorphic, formal, and CR mappings between such manifolds. In this paper we present a theory of iterated Segre…

Complex Variables · Mathematics 2007-05-23 M. S. Baouendi , P. Ebenfelt , Linda Preiss Rothschild