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Related papers: A remark on minimal Fano threefolds

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We study Fano threefolds with~terminal singularities admitting a "minimal" action of a finite group. We prove that under certain additional assumptions such a variety does not contain planes. We also obtain an upper bounds of the number of…

Algebraic Geometry · Mathematics 2019-08-14 Yuri Prokhorov

In 1949 Fano published his last paper on $3$-folds with canonical sectional curves. There he constructed and described a $3$-fold of the type $X^{22}_3$ in ${\mathbb P}^{13}$ with canonical curve section, which we like to call Fano's last…

Algebraic Geometry · Mathematics 2022-12-20 Marco Andreatta , Roberto Pignatelli

A minimal presentation of the cohomology ring of the flag manifold $GL_n/B$ was given in [A. Borel, 1953]. This presentation was extended by [E. Akyildiz-A. Lascoux-P. Pragacz, 1992] to a non-minimal one for all Schubert varieties. Work of…

Combinatorics · Mathematics 2024-03-25 Avery St. Dizier , Alexander Yong

A Fano surface of a smooth cubic threefold X in P^4 parametrizes the lines on X. In this note, we prove that a Fano surface satisfies the Tate conjecture over a field of finite type over the prime field and characteristic not 2.

Algebraic Geometry · Mathematics 2013-04-16 Xavier Roulleau

We briefly review the formal picture in which a Calabi-Yau $n$-fold is the complex analogue of an oriented real $n$-manifold, and a Fano with a fixed smooth anticanonical divisor is the analogue of a manifold with boundary, motivating a…

Algebraic Geometry · Mathematics 2007-05-23 R. P. Thomas

To every elliptic Calabi-Yau threefold with a section $X$ there can be associated a Lie group $G$ and a representation $\rho$ of that group. The group is determined from the Weierstrass model, which has singularities that are generically…

Algebraic Geometry · Mathematics 2016-09-07 Antonella Grassi , David R. Morrison

We show that the $\mathbb{Q}$-Fano index of a canonical weak Fano $3$-fold is at most $66$. This upper bound is optimal and gives an affirmative answer to a conjecture of Chengxi Wang in dimension $3$. During the proof, we establish a new…

Algebraic Geometry · Mathematics 2025-10-21 Chen Jiang , Haidong Liu

The long-standing topological Tverberg conjecture claimed, for any continuous map from the boundary of an $N(q,d):=(q-1)(d+1)$-simplex to $d$-dimensional Euclidian space, the existence of $q$ pairwise disjoint subfaces whose images have…

Combinatorics · Mathematics 2018-08-23 Steven Simon

This article constructs a smooth weak Fano threefold of Picard number two with small anti-canonical morphism that arises as a blowup of a smooth curve of genus 5 and degree 8 in $\mathbb{P}^3$. While the existence of this weak Fano was…

Algebraic Geometry · Mathematics 2018-01-22 Joseph W. Cutrone , Michael A. Limarzi , Nicholas A. Marshburn

We study moduli spaces of stable objects in the Kuznetsov components of Fano threefolds. We prove a general non-emptiness criterion for moduli spaces, which applies to the cases of prime Fano threefolds of index $1$, degree $10 \leq d \leq…

Algebraic Geometry · Mathematics 2024-06-14 Chunyi Li , Yinbang Lin , Laura Pertusi , Xiaolei Zhao

We establish the real integral Hodge conjecture for 1-cycles on various classes of uniruled threefolds (conic bundles, Fano threefolds with no real point, some del Pezzo fibrations) and on conic bundles over higher-dimensional bases which…

Algebraic Geometry · Mathematics 2020-10-20 Olivier Benoist , Olivier Wittenberg

Let $(X,\Delta)$ be an $n$-dimensional $\epsilon$-klt log $\QQ$-Fano pair. We give an upper bound for the volume ${\rm Vol}(-(K_X+\Delta))=(-(K_X+\Delta))^n$ when $n=2$ or $n=3$ and $X$ is {$\QQ$-factorial} of $\rho(X)=1$. This bound is…

Algebraic Geometry · Mathematics 2012-04-13 Ching-Jui Lai

We introduce a concept of minimality for Fano polygons. We show that, up to mutation, there are only finitely many Fano polygons with given singularity content, and give an algorithm to determine the mutation-equivalence classes of such…

Algebraic Geometry · Mathematics 2022-10-28 Alexander Kasprzyk , Benjamin Nill , Thomas Prince

Over an algebraically closed field of positive characteristic, we classify smooth Fano threefolds of Picard number one whose anti-canonical linear systems are not very ample. Furthermore, we also prove that an anti-canonically embedded Fano…

Algebraic Geometry · Mathematics 2026-03-13 Hiromu Tanaka

In a work of Costa and Mir\'{o}-Roig state the following conjecture: Every smooth complete toric Fano variety has a full strongly exceptional collection of line bundles. The goal of this article is to prove it for toric Fano 3-folds.

Algebraic Geometry · Mathematics 2010-12-30 Alessandro Bernardi , Sofia Tirabassi

We provide an outline of the proof of the Donovan--Wemyss Conjecture in the context of the Homological Minimal Model Program for threefolds. The proof relies on results of August, of Hua and the second-named author, Wemyss, and on the…

Algebraic Geometry · Mathematics 2025-01-03 Gustavo Jasso , Bernhard Keller , Fernando Muro

This thesis is an investigation of the moduli spaces of instanton bundles on the Fano threefold $Y_5$ (a linear section of $\mathbb{G}r(2,5)$). It contains new proofs of classical facts about lines, conics and cubics on $Y_5$, and about…

Algebraic Geometry · Mathematics 2014-12-01 Giangiacomo Sanna

We study a subclass of K\"ahler-Einstein Fano polygons and how they behave under mutation. The polygons of interest are K\"ahler-Einstein Fano triangles and symmetric Fano polygons. In particular, we find an explicit bound for the number of…

Combinatorics · Mathematics 2024-02-06 Thomas Hall

The Castelnuovo bound conjecture, which is proposed by physicists, predicts an effective vanishing result for Gopakumar-Vafa invariants of Calabi-Yau 3-folds of Picard number one. Previously, it is only known for a few cases and all the…

Algebraic Geometry · Mathematics 2024-07-30 Zhiyu Liu

We show that for a weak $\mathbb{Q}$-Fano threefold $X$ of Picard rank two ($\mathbb{Q}$-factorial with at worst terminal singularities), the anticanonical volume satisfies $-K_X^3\leq72$ except in one case, and the equality holds only if…

Algebraic Geometry · Mathematics 2025-01-23 Ching-Jui Lai