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Related papers: Cohomological obstructions to equivariant uniratio…

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We study unirationality of actions of finite groups on Fano threefolds.

Algebraic Geometry · Mathematics 2025-02-28 Ivan Cheltsov , Yuri Tschinkel , Zhijia Zhang

We develop an equivariant version of the formalism of intermediate Jacobian torsor obstructions, and apply it to conic bundles over rational surfaces, quadric surface bundles over $\mathbb P^1$, and Fano threefolds.

Algebraic Geometry · Mathematics 2025-03-20 Tudor Ciurca , Sho Tanimoto , Yuri Tschinkel

We introduce a torsor-theoretic obstruction to equivariant unirationality and show that it is also sufficient for actions of finite groups on toric varieties arising from automorphisms of the torus.

Algebraic Geometry · Mathematics 2025-06-10 Andrew Kresch , Yuri Tschinkel

We study equivariant unirationality of actions of finite groups on tori of small dimensions.

Algebraic Geometry · Mathematics 2025-09-23 Yuri Tschinkel , Zhijia Zhang

This is a survey on the equivariant cohomology of Lie group actions on manifolds, from the point of view of de Rham theory. Emphasis is put on the notion of equivariant formality, as well as on applications to ordinary cohomology and to…

Differential Geometry · Mathematics 2019-03-29 Oliver Goertsches , Leopold Zoller

We generalize the equivariant intermediate Jacobian torsor obstruction over $\mathbb{C}$ to algebraically closed fields of characteristic zero. It is an obstruction to the (projective) linearizability problem of finite group actions on…

Algebraic Geometry · Mathematics 2026-01-13 Shuto Abe

We complete the classification of regular generically free actions of finite groups on del Pezzo surfaces, up to birational equivalence. As a byproduct, we settle several open problems in equivariant birational geometry, e.g., we classify…

Algebraic Geometry · Mathematics 2026-04-23 Ivan Cheltsov , Yuri Tschinkel , Zhijia Zhang

We study a double solid X branched along a nodal sextic surface in a projective space and the 2-torsion subgroup in the third integer cohomology group of a resolution of singularities of X. This group can be considered as an obstruction to…

Algebraic Geometry · Mathematics 2019-09-16 Alexandra Kuznetsova

Fix a finite group $G$. We seek to classify varieties with $G$-action equivariantly birational to a representation of $G$ on affine or projective space. Our focus is odd-dimensional smooth complete intersections of two quadrics, relating…

Algebraic Geometry · Mathematics 2022-02-02 Brendan Hassett , Yuri Tschinkel

We study equivariant birationality from the perspective of derived categories. We produce examples of nonlinearizable but stably linearizable actions of finite groups on smooth cubic fourfolds.

Algebraic Geometry · Mathematics 2023-04-19 Christian Böhning , Hans-Christian Graf von Bothmer , Yuri Tschinkel

We show that polarized endomorphisms of rationally connected threefolds with at worst terminal singularities are equivariantly built up from those on Q-Fano threefolds, Gorenstein log del Pezzo surfaces and P^1. Similar results are obtained…

Algebraic Geometry · Mathematics 2019-02-20 De-Qi Zhang

We study linearizability of actions of finite groups on cubic threefolds with non-isolated singularities.

Algebraic Geometry · Mathematics 2025-05-08 Ivan Cheltsov , Lisa Marquand , Yuri Tschinkel , Zhijia Zhang

We study linearizability of actions of finite groups on singular cubic threefolds, using cohomological tools, intermediate Jacobians, Burnside invariants, and the equivariant Minimal Model Program.

Algebraic Geometry · Mathematics 2025-01-07 Ivan Cheltsov , Yuri Tschinkel , Zhijia Zhang

We classify equivariantly Gorenstein log del Pezzo surfaces with boundaries at infinity and with finite group actions such that the quotient surface modulo the finite group has Picard number one. We also determine the corresponding finite…

Algebraic Geometry · Mathematics 2007-05-23 Masayoshi Miyanishi , De-Qi Zhang

A variety X with an action of a finite group G is said to be G-unirational if there is a G-equivariant dominant rational map V -> X where V is a faithful linear representation of G. This generalizes the usual notion of unirationality. We…

Algebraic Geometry · Mathematics 2016-10-04 Alexander Duncan

We study degree of irrationality of quasismooth anticanonically embedded weighted Fano 3-fold hypersurfaces that have terminal singularities.

Algebraic Geometry · Mathematics 2022-10-27 Ivan Cheltsov , Jihun Park

We study the spaces of rational curves on Fano threefolds with Gorenstein terminal singularities. We generalize the results regarding Geometric Manin's Conjecture for smooth Fano threefolds, including the classification of subvarieties with…

Algebraic Geometry · Mathematics 2025-05-23 Fumiya Okamura

We study linearizability of actions of finite groups on cubic threefolds with nonnodal isolated singularities.

Algebraic Geometry · Mathematics 2025-11-14 Ivan Cheltsov , Lisa Marquand , Yuri Tschinkel , Zhijia Zhang

We introduce an equivariant version of Hochschild cohomology as the deformation cohomology to study equivariant deformations of associative algebras equipped with finite group actions.

Rings and Algebras · Mathematics 2018-04-17 Goutam Mukherjee , Raj Bhawan Yadav

We investigate equivariant birational geometry of rational surfaces and threefolds from the perspective of derived categories.

Algebraic Geometry · Mathematics 2023-11-28 Christian Böhning , Hans-Christian Graf von Bothmer , Yuri Tschinkel
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