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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

An almost Fano bundle is a vector bundle on a smooth projective variety that its projectivization is an almost Fano variety. In this paper, we prove that almost Fano bundles exist only on almost Fano manifolds and study rank 2 almost Fano…

Algebraic Geometry · Mathematics 2010-04-21 Kazunori Yasutake

We establish sharp upper and lower bounds for the number of rational points of bounded anticanonical height on a smooth bihomogeneous threefold defined over Q and of bidegree (1, 2). These bounds are in agreement with Manin's conjecture.

Number Theory · Mathematics 2013-08-02 Pierre Le Boudec

We study the connectedness of the real locus of smooth geometrically rational Fano threefolds and prove a sufficient criterion of $\mathbb{R}$-rationality.

Algebraic Geometry · Mathematics 2025-07-08 Andrea Fanelli , Frédéric Mangolte

We investigate the variation of log canonical thresholds in (graded) linear systems. For toric log Fano varieties, we give a sharp lower bound for log canonical thresholds of the anticanonical members in terms of the global minimal log…

Algebraic Geometry · Mathematics 2014-11-12 Florin Ambro

The generating series of descendent invariants of stable pairs on 3-folds is conjectured to be rational and to satisfy a $q\leftrightarrow q^{-1}$ symmetry. We prove this conjecture for Fano 3-folds. We utilize the same path of stability…

Algebraic Geometry · Mathematics 2026-04-08 Ivan Karpov , Miguel Moreira

Balanced linear models with fixed effects are taught in undergraduate programs of all universities. These occur in experimental designs such as one-way and two-way Anova, randomized complete block designs (RCBD) and split plot designs. The…

Statistics Theory · Mathematics 2022-12-12 Martin Bilodeau

The paper concerns foundations of sensitivity and stability analysis in optimization and related areas, being primarily addressed truncated constrained systems. We consider general models, which are described by multifunctions between…

Optimization and Control · Mathematics 2025-04-30 Boris S. Mordukhovich , Pengcheng Wu , Xiaoqi Yang

We give a formula relating the total Tjurina number and the generic splitting type of the bundle of logarithmic vector fields associated to a reduced plane curve. By using it, we give a characterization of nearly free curves in terms of…

Algebraic Geometry · Mathematics 2019-09-17 Takuro Abe , Alexandru Dimca

The Manin-Peyre conjecture is established for smooth spherical Fano threefolds of semisimple rank one and type N. Together with the previously solved case T and the toric cases, this covers all types of smooth spherical Fano threefolds. The…

Number Theory · Mathematics 2024-06-14 Valentin Blomer , Jörg Brüdern , Ulrich Derenthal , Giuliano Gagliardi

For a generic anti-canonical hypersurface in each smooth toric Fano 4-fold with rank 2 Picard group, we prove there exist three isolated rational curves in it. Moreover, for all these 4-folds except one, the contractions of generic…

Algebraic Geometry · Mathematics 2010-12-21 Jinxing Xu

Motivated by the appearance of fractional powers of line bundles in studies of vector-like spectra in 4d F-theory compactifications, we analyze the structure and origin of these bundles. Fractional powers of line bundles are also known as…

High Energy Physics - Theory · Physics 2021-10-04 Martin Bies , Mirjam Cvetič , Ron Donagi , Muyang Liu , Marielle Ong

We test numerically the refined Manin's conjecture about the asymptotics of points of bounded height on Fano varieties for some diagonal cubic surfaces.

Algebraic Geometry · Mathematics 2007-05-23 Emmanuel Peyre , Yuri Tschinkel

Let $X$ be a projective Fano manifold of Picard number one, different from the projective space. There is a folklore conjecture that any non-constant endomorphism of $X$ is an isomorphism. In the first half of this article, we will prove…

Algebraic Geometry · Mathematics 2023-08-08 Sarbeswar Pal

We consider weak Fano manifolds with small contractions obtained by blowing up successively curves and subvarieties of codimension 2 in products of projective spaces. We give a classification result for a special case. In the process of…

Algebraic Geometry · Mathematics 2016-10-25 Toru Tsukioka

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 find a relation between a cubic hypersurface $Y$ and its Fano variety of lines $F(Y)$ in the Grothendieck ring of varieties. We prove that if the class of an affine line is not a zero-divisor in the Grothendieck ring of varieties, then…

Algebraic Geometry · Mathematics 2014-06-27 Sergey Galkin , Evgeny Shinder

Denote by $E_r$ the $r^{th}$ elementary symmetric polynomial in $\dim V$ variables for a vector space $V$ over an infinite field $\Bbbk$. We describe the rational points on the Fano scheme $F_{d-1}(Z(E_{\dim V-1}))$ of projective…

Algebraic Geometry · Mathematics 2025-08-06 Alexandru Chirvasitu

Cylinders in Fano varieties receives a lot of attentions recently from the viewpoints of birational geometry and unipotent geometry. In this article, we provide a survey of several known et new results concerning the anti-canonically polar…

Algebraic Geometry · Mathematics 2026-03-13 Adrien Dubouloz , In-Kyun Kim , Takashi Kishimoto , Joonyeong Won

We study the behavior of toric Landau-Ginzburg models under extremal contraction and minimal model program. We also establish a relation between the moduli space of toric Landau-Ginzburg models and the geography of central models. We…

Algebraic Geometry · Mathematics 2025-07-04 Yang He , Artan Sheshmani