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In this paper, we show that general Fano complete intersections over an algebraically closed field of arbitrary characteristics are separably rationally connected. Our proof also implies that general log Fano complete intersections with…

Algebraic Geometry · Mathematics 2015-07-03 Qile Chen , Yi Zhu

We generalize the Fenchel theorem for strong spacelike closed curves of index $1$ in the 3-dimensional Minkowski space, showing that the total curvature must be less than or equal to $2\pi$. Here strong spacelike means that the tangent…

Differential Geometry · Mathematics 2016-03-28 Nan Ye , Xiang Ma

Consider the Fano scheme $F_k(Y)$ parameterizing $k$-dimensional linear subspaces contained in a complete intersection $Y \subset \mathbb{P}^m$ of multi-degree $\underline{d} = (d_1, \ldots, d_s)$. It is known that, if $t := \sum_{i=1}^s…

Algebraic Geometry · Mathematics 2018-12-18 Francesco Bastianelli , Ciro Ciliberto , Flaminio Flamini , Paola Supino

This article introduces and studies the tight approximation property, a property of algebraic varieties defined over the function field of a complex or real curve that refines the weak approximation property (and the known cohomological…

Algebraic Geometry · Mathematics 2024-06-18 Olivier Benoist , Olivier Wittenberg

In this article, we prove that any $\Bbb Q$-factorial weak Fano 3-fold with only terminal singularities has a smoothing.

Algebraic Geometry · Mathematics 2007-05-23 Tatsuhiro Minagawa

We give necessary and sufficient topological conditions for a simple closed curve on a real rational surface to be approximable by smooth rational curves. We also study approximation by smooth rational curves with given complex…

Algebraic Geometry · Mathematics 2025-05-26 János Kollár , Frédéric Mangolte

A Fano problem is an enumerative problem of counting $r$-dimensional linear subspaces on a complete intersection in $\mathbb{P}^n$ over a field of arbitrary characteristic, whenever the corresponding Fano scheme is finite. A classical…

Algebraic Geometry · Mathematics 2020-11-24 Sachi Hashimoto , Borys Kadets

We consider the problem of minimizing a convex function over the intersection of finitely many simple sets which are easy to project onto. This is an important problem arising in various domains such as machine learning. The main difficulty…

Optimization and Control · Mathematics 2017-10-19 Achintya Kundu , Francis Bach , Chiranjib Bhattacharyya

Over the function field of a complex algebraic curve, strong approximation off a non-empty finite set of places holds for the complement of a codimension $2$ closed subset in a homogeneous space under a semisimple algebraic group, and for…

Algebraic Geometry · Mathematics 2024-06-25 Elyes Boughattas

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

For $n\geq 4$, let $X$ be a complex smooth Fano $n$-fold whose minimal anticanonical degree of non-free rational curves on $X$ is at least $n-2$. We classify extremal contractions of such varieties. As an application, we obtain a…

Algebraic Geometry · Mathematics 2024-06-04 Kiwamu Watanabe

We prove that the derived category of a smooth complete intersection variety is equivalent to a full subcategory of the derived category of a smooth projective Fano variety. This enables us to define some new invariants of smooth projective…

Algebraic Geometry · Mathematics 2015-04-30 Young-Hoon Kiem , In-Kyun Kim , Hwayoung Lee , Kyoung-Seog Lee

It is known since the work of Frankel that two compactly immersed minimal hypersurfaces in a manifold with positive Ricci curvature must have an intersection point. Several generalizations of this result can be found in the literature, for…

Differential Geometry · Mathematics 2020-04-20 Renan Assimos

We have derived that on certain Banach spaces having a graph structure $G$, the iterations for asymptotically $G$-nonexpansive map will converge weakly towards a fixed point. This result unifies and extends several theorems on fixed points…

Functional Analysis · Mathematics 2022-02-28 Asrifa Sultana

Let $X$ be a $\mathbb Q$-factorial canonical weak Fano variety of dimension $n\geq 2$. We show that if the $\mathbb Q$-Fano index $q_{\mathbb Q}(X)\geq 3$, then $X$ satisfies a Kawamata--Miyaoka type inequality: \[c_1(X)^n\leq 4\,\hat…

Algebraic Geometry · Mathematics 2025-11-18 Haidong Liu

Using ideas from the theory of tropical curves and degeneration, we prove that any Fano hypersurface (and more generally Fano complete intersections) is swept by at most quadratic rational curves.

Algebraic Geometry · Mathematics 2011-08-23 Takeo Nishinou

Let X be a complex Fano manifold of dimension n. Let s(X) be the sum of l(R)-1 for all the extremal rays of X, the edges of the cone NE(X) of curves of X, where l(R) denotes the minimum of (-K_X \cdot C) for all rational curves C whose…

Algebraic Geometry · Mathematics 2013-10-01 Kento Fujita

We study the weakest convergence-type conditions for fixed point results for Banach and Kannan mappings. Building on Suzuki's weakest condition for Banach mappings and our previous result for Kannan mappings, we compare convergence…

Functional Analysis · Mathematics 2026-05-13 Shunya Hashimoto , Misako Kikkawa , Shuji Machihara , Aqib Saghir

A nef-partition for a weighted complete intersection is a combinatorial structure on its weights and degrees which is important for Mirror Symmetry. It is known that nef-partitions exist for smooth well-formed Fano weighted complete…

Algebraic Geometry · Mathematics 2023-12-13 Mikhail Ovcharenko

This paper is motivated by Davenport's problem and the subsequent work regarding badly approximable points in submanifolds of a Euclidian space. We study the problem in the area of twisted Diophantine approximation and present two different…

Number Theory · Mathematics 2017-05-17 Paloma Bengoechea , Nikolay Moshchevitin , Natalia Stepanova