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The purpose of this note is to prove Grothendieck's standard conjectures for the Fano variety of lines on a smooth cubic hypersurface in projective space.

Algebraic Geometry · Mathematics 2017-06-22 Humberto A. Diaz

We study Fano varieties endowed with a faithful action of a symmetric group, as well as analogous results for Calabi--Yau varieties, and log terminal singularities. We show the existence of a constant $m(n)$, so that every symmetric group…

Algebraic Geometry · Mathematics 2025-02-05 Louis Esser , Lena Ji , Joaquín Moraga

Real Legendrian subvarieties are classical objects of differential geometry and classical mechanics and they have been studied since antiquity. However, complex Legendrian subvarieties are much more rigid and have more exceptional…

Algebraic Geometry · Mathematics 2013-05-16 Jarosław Buczyński

We show that the anti-canonical volume of an $n$-dimensional K\"ahler-Einstein $\mathbb{Q}$-Fano variety is bounded from above by certain invariants of the local singularities, namely $\mathrm{lct}^n\cdot\mathrm{mult}$ for ideals and the…

Algebraic Geometry · Mathematics 2019-02-20 Yuchen Liu

High refractive index dielectric nanostructures provide original optical properties thanks to the occurrence of size- and shape-dependent optical resonance modes. These modes commonly present a spectral overlap of broad, low-order modes…

We give an upper bound for the minimal discrepancies of hypersurface singularities. As an application, we show that Shokurov's conjecture is true for log-terminal threefolds.

alg-geom · Mathematics 2007-05-23 Vladimir Masek

An ultra-compact one-dimensional topological photonic crystal (1D-TPC) is designed in a single mode silicon bus-waveguide to generate Fano resonance lineshape. The Fano resonance comes from the interference between the discrete topological…

In this paper we consider double covers of the projective space in relation with the problem of extensions of varieties, specifically of extensions of canonical curves to $K3$ surfaces and Fano 3-folds. In particular we consider $K3$…

Algebraic Geometry · Mathematics 2022-05-17 Ciro Ciliberto , Thomas Dedieu

Three different periodic optical metasurfaces exhibiting Fano resonances are studied in mid-IR frequency range in the presence of a substrate. We develop a rigorous semi-analytical technique and calculate how the presence of a substrate…

Optics · Physics 2012-04-16 S. Hossein Mousavi , Alexander B. Khanikaev , Gennady Shvets

We give an explicit characterization on the singularities of exceptional pairs in any dimension. In particular, we show that any exceptional Fano surface is $\frac{1}{42}$-lc. As corollaries, we show that any $\mathbb R$-complementary…

Algebraic Geometry · Mathematics 2023-05-30 Jihao Liu

We construct first examples of Fano varieties with torsion in their third cohomology group. The examples are constructed as double covers of linear sections of rank loci of symmetric matrices, and can be seen as higher-dimensional analogues…

Algebraic Geometry · Mathematics 2023-11-17 John Christian Ottem , Jørgen Vold Rennemo

We give the first examples of flat fiber type contractions of Fano manifolds onto varieties that are not weak Fano, and we prove that these morphisms are Fano conic bundles. We also review some known results about the interaction between…

Algebraic Geometry · Mathematics 2017-03-09 Eleonora Anna Romano

Alex Waldron proved that for sufficiently general degree $d$ hypersurfaces in projective $n$-space, the Fano scheme parameterizing $r$-dimensional linear spaces contained in the hypersurface is nonempty precisely for the degree range $n\geq…

Algebraic Geometry · Mathematics 2017-03-10 Jason Michael Starr

We classify some special classes of non-rational Fano threefolds with terminal singularities. In particular, all such hyperelliptic and trigonal varieties are found.

Algebraic Geometry · Mathematics 2019-07-15 Yuri Prokhorov

We classify smooth Fano manifolds X with the Picard number $\rho_X \geq 3$ such that there exists an extremal ray which has a birational contraction that maps a divisor to a point.

Algebraic Geometry · Mathematics 2012-12-21 Kento Fujita

We characterize the birational geometry of some hyperk\"ahler fourfolds of Picard rank $3$ obtained as the Fano varieties of lines on cubic fourfolds containing pairs of cubic scrolls. In each of the two cases considered, we identify all of…

Algebraic Geometry · Mathematics 2025-09-10 Corey Brooke , Sarah Frei , Lisa Marquand , Xuqiang Qin

We prove that the lengths of extremal rays of log canonical Fano surfaces with Picard number one satisfy the ascending chain condition. This confirms the 2-dimensional case of a conjecture stated by Fujino and Ishitsuka

Algebraic Geometry · Mathematics 2014-10-27 Evgeny Mayanskiy

A Fano variety of Picard number $1$ is said to be \textit{birationally solid} if it is not birational to a Mori fiber space over a positive dimensional base. In this paper we complete the classification of quasi-smooth birationally solid…

Algebraic Geometry · Mathematics 2023-09-12 Takuzo Okada

Let $X$ be a cubic fourfold that has only simple singularities and does not contain a plane. We prove that the Fano variety of lines on $X$ has the same analytic type of singularity as the Hilbert scheme of two points on a surface with only…

Algebraic Geometry · Mathematics 2018-04-03 Ryo Yamagishi

We give some bounds on the anticanonical degrees of Fano varieties with Picard number 1 and mild singularities, extending results of Koll\'ar et al. from the early 90's and improving them even in the smooth case. The proof is based on a…

Algebraic Geometry · Mathematics 2007-05-23 Ziv Ran , Herb Clemens