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Related papers: Boundedness theorem for Fano log-threefolds

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We prove that in any fixed dimension, K-semistable log Fano cone singularities whose volumes are bounded from below by a fixed positive number form a bounded set. As a consequence, we show that the set of local volumes of klt singularities…

Algebraic Geometry · Mathematics 2024-08-22 Chenyang Xu , Ziquan Zhuang

We prove that a weak $\mathbb{Q}$-Fano $3$-fold with terminal singularities has unobstructed deformations. By using this result and computing some invariants of a terminal singularity, we provide two results on global deformation of a weak…

Algebraic Geometry · Mathematics 2017-09-12 Taro Sano

We study unirationality and rationality of Fano threefolds of degree 18 over nonclosed fields.

Algebraic Geometry · Mathematics 2019-10-31 Brendan Hassett , Yuri Tschinkel

In this short note, we give an alternative proof of the semipositivity of the Chow-Mumford line bundle for families of K-semistable log-Fano pairs, and of the nefness threeshold for the log-anti-canonical line bundle on families of K-stable…

Algebraic Geometry · Mathematics 2023-07-14 Giulio Codogni , Zsolt Patakfalvi

We show that in any sequence of a general type MMP, the minimal log discrepancy of singularities takes at most finitely many values, and the fibers of all the extremal contractions and flips belong to a bounded family. A key ingredient in…

Algebraic Geometry · Mathematics 2025-09-03 Jingjun Han , Lu Qi , Ziquan Zhuang

This survey paper reports on work of Birkar, who confirmed a long-standing conjecture of Alexeev and Borisov-Borisov: Fano varieties with mild singularities form a bounded family once their dimension is fixed. Following Prokhorov-Shramov,…

Algebraic Geometry · Mathematics 2021-02-02 Stefan Kebekus

We classify smooth Fano threefolds with infinite automorphism groups.

Algebraic Geometry · Mathematics 2021-06-11 Ivan Cheltsov , Victor Przyjalkowski , Constantin Shramov

We explain an effective Kawamata boundedness result for Mori-Fano 3-folds. In particular, we describe a list of 39,550 possible Hilbert series of semistable Mori-Fano 3-folds, with examples to explain its meaning, its relationship to known…

Algebraic Geometry · Mathematics 2022-01-19 Gavin Brown , Alexander Kasprzyk

We show that the total Cartier index of varieties with rational singularities in a bounded family is bounded. This solves a problem of Han and Jiang. The overall structure of the proof, which treats the surface case and the…

Algebraic Geometry · Mathematics 2026-05-22 Jihao Liu , Ruicheng Hu , Sheng Qin

We prove the $W\mathcal{O}$-rationality of klt threefolds and the rational chain connectedness of klt Fano threefolds over a perfect field of characteristic $p>5$. As a consequence, any klt Fano threefold over a finite field has a rational…

Algebraic Geometry · Mathematics 2016-12-01 Yoshinori Gongyo , Yusuke Nakamura , Hiromu Tanaka

We study smoothings of Fano threefolds. We prove that the Picard number remains constant in the case of terminal Gorenstein singularities.

Algebraic Geometry · Mathematics 2007-05-23 Priska Jahnke , Ivo Radloff

We prove that for any e>0, there exists only finitely many e-log terminal spherical Fano varieties of fixed dimension. We also introduce an invariant of a spherical subgroup H in a reductive group G which measures how nice an equivariant…

Algebraic Geometry · Mathematics 2007-05-23 Valery Alexeev , Michel Brion

In this paper, we study boundedness questions for (simply-connected) smooth Calabi-Yau threefolds. The diffeomorphism class of such a threefold is known to be determined up to finitely many possibilities by the integral middle cohomology…

Algebraic Geometry · Mathematics 2023-04-26 P. M. H. Wilson

Studying Manin's program for a family of spherical log Fano threefolds, we determine the asymptotic number of integral points whose height associated with an arbitrary ample line bundle is bounded. This confirms a recent conjecture by…

Number Theory · Mathematics 2025-05-16 Ulrich Derenthal , Florian Wilsch

In this paper I study the rationality problem for Fano threefolds $X\subset \p^{p+1}$ of genus $p$, that are Gorenstein, with at most canonical singularities. The main results are: (1) a trigonal Fano threefold of genus $p$ is rational as…

Algebraic Geometry · Mathematics 2023-06-08 Ciro Ciliberto

We give a self-contained and simplified proof of Mukai's classification of prime Fano threefolds of index 1 and genus $g \ge 6$ with at most Gorenstein factorial terminal singularities, and of its extension to higher-dimension.

Algebraic Geometry · Mathematics 2025-07-01 Arend Bayer , Alexander Kuznetsov , Emanuele Macrì

We discuss boundedness of toric Fano foliations and connectedness of its dicritical and singular loci. Moreover, we show the set of interpolated $\delta$-lcts for the toric foliations satisfies the descending chain condition.

Algebraic Geometry · Mathematics 2025-02-18 Chih-Wei Chang , Yen-An Chen

In this paper, we prove that the family of $\Bbb Q$-Fano threefolds with Picard number one is birationally unbounded.

Algebraic Geometry · Mathematics 2007-05-23 Jiayuan Lin

We prove that Generalized Mukai Conjecture holds for Fano manifolds $X$ of pseudoindex $i_X \ge (\dim X +3)/3$. We also give different proofs of the conjecture for Fano fourfolds and fivefolds.

Algebraic Geometry · Mathematics 2009-12-14 Carla Novelli , Gianluca Occhetta

We give necessary and sufficient conditions for unirationality and rationality of Fano threefolds of geometric Picard rank-1 over an arbitrary field of zero characteristic.

Algebraic Geometry · Mathematics 2021-04-29 Alexander Kuznetsov , Yuri Prokhorov