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We explicitly construct a symplectomorphism that relates magnetic twists to the invariant hyperk\"ahler structure of the tangent bundle of a Hermitian symmetric space. This symplectomorphism reveals foliations by (pseudo-) holomorphic…

Symplectic Geometry · Mathematics 2024-06-25 Johanna Bimmermann

We show that the secant variety of a linearly normal smooth curve of degree at least 2g+3 is arithmetically Cohen-Macaulay, and we use this information to study the graded Betti numbers of the secant variety.

Algebraic Geometry · Mathematics 2012-01-25 Jessica Sidman , Peter Vermeire

We systematically study the moduli theory of symplectic varieties (in the sense of Beauville) which admit a resolution by an irreducible symplectic manifold. In particular, we prove an analog of Verbitsky's global Torelli theorem for the…

Algebraic Geometry · Mathematics 2021-01-07 Benjamin Bakker , Christian Lehn

We proof here the existence of a topological thick and thin decomposition of any closed definable thick isolated singularity germ in the spirit of the recently discovered metric thick and thin decomposition of complex normal surface…

Metric Geometry · Mathematics 2012-08-22 Lev Birbrair , Alexandre Fernandes , Vincent Grandjean

Bondal claims that for a smooth toric variety $X$, its bounded derived category of coherent sheaves $D_{c}^{b}(X)$ is generated by the Thomsen collection $T(X)$ of line bundles obtained as direct summands of the pushforward of…

Algebraic Geometry · Mathematics 2025-12-10 Xiaodong Yi

In this paper we present an effective method for linearizing rational varieties of codimension at least two under Cremona transformations, starting from a given parametrization. Using these linearizing Cremonas, we simplify the equations of…

Algebraic Geometry · Mathematics 2014-11-18 Ciro Ciliberto , Maria Angelica Cueto , Massimiliano Mella , Kristian Ranestad , Piotr Zwiernik

We prove a theorem relating torus-equivariant coherent sheaves on toric varieties to polyhedrally-constructible sheaves on a vector space. At the level of K-theory, the theorem recovers Morelli's description of the K-theory of a smooth…

Algebraic Geometry · Mathematics 2011-09-23 Bohan Fang , Chiu-Chu Melissa Liu , David Treumann , Eric Zaslow

Let $X \subset Y$ be closed (possibly singular) subschemes of a smooth projective toric variety $T$. We show how to compute the Segre class $s(X,Y)$ as a class in the Chow group of $T$. Building on this, we give effective methods to compute…

Algebraic Geometry · Mathematics 2019-05-31 Corey Harris , Martin Helmer

Going one step further in Zak's classification of Scorza varieties with secant defect equal to one, we characterize the Veronese embedding of $\P^n$ given by the complete linear system of quadrics and its smooth projections from a point as…

Algebraic Geometry · Mathematics 2014-07-23 Roberto Munoz , Jose Carlos Sierra , Luis Eduardo Sola Conde

Given a smooth projective toric variety $X$ of Picard rank 2, we resolve the diagonal sheaf on $X \times X$ by a linear complex of length $\dim{X}$ consisting of finite direct sums of line bundles. As applications, we prove a new case of a…

Algebraic Geometry · Mathematics 2024-10-24 Michael K. Brown , Mahrud Sayrafi

We study the local cohomology modules for the secant variety of lines of a smooth projective variety $Y$ and for higher secant varieties of smooth projective curves. We show that the local cohomological defect in the first case is related…

Algebraic Geometry · Mathematics 2026-02-05 Qianyu Chen , Bradley Dirks , Sebastian Olano , Debaditya Raychaudhury

Logarithmic and $b$-tangent bundles provide a versatile framework for addressing singularities in geometry. Introduced by Deligne and Melrose, these modified bundles resolve singularities by reframing singular vector fields as well-behaved…

Differential Geometry · Mathematics 2025-02-27 Eva Miranda , Pablo Nicolás

Given a variety defined over a field of characteristic zero and an algebraically integrable foliation of corank less than or equal to two, we show the existence of a categorical quotient, defined on the non-empty open set of stable points,…

Algebraic Geometry · Mathematics 2021-10-13 Federico Bongiorno

We determine which tangential varieties of homogeneously embedded rational homogeneous varieties are spherical. We determine the homogeneous coordinate rings and rings of covariants of the tangential varieties of homogenously embedded…

Algebraic Geometry · Mathematics 2007-05-23 J. M. Landsberg , Jerzy Weyman

In this paper, we prove that: For any given finitely many distinct points $P_1,...,P_r$ and a closed subvariety $S$ of codimension $\geq 2$ in a complete toric variety over a uncountable (characteristic 0) algebraically closed field, there…

Algebraic Geometry · Mathematics 2009-05-12 Yifei Chen , Vyacheslav Shokurov

From a finite set in a lattice, we can define a toric variety embedded in a projective space. In this paper, we give a combinatorial description of the dual defect of the toric variety using the structure of the finite set as a Cayley sum…

Algebraic Geometry · Mathematics 2019-12-12 Katsuhisa Furukawa , Atsushi Ito

An algebraic subvariety Z of A_g is totally geodesic if it is the image via the natural projection map of some totally geodesic submanifold X of the Siegel space. We say that X is the symmetric space uniformizing Z. In this paper we…

Algebraic Geometry · Mathematics 2020-10-27 Carolina Tamborini

We survey some recent results concerning the so called Categorical Torelli problem. This is to say how one can reconstruct a smooth projective variety up to isomorphism, by using the homological properties of special admissible…

Algebraic Geometry · Mathematics 2022-08-31 Laura Pertusi , Paolo Stellari

This paper gives methods for understanding invariants of symplectic quotients. The symplectic quotients considered here are compact symplectic manifolds (or more generally orbifolds), which arise as the symplectic quotients of a symplectic…

Symplectic Geometry · Mathematics 2007-05-23 Shaun Martin

Toric varieties are a special class of rational varieties defined by equations of the form {\it monomial = monomial}. For a good brief survey of the history and role of toric varieties see [10]. Any toric variety $X$ contains a cover by…

alg-geom · Mathematics 2008-02-03 Frank DeMeyer , Tim Ford , Rick Miranda