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We show that if the variety of minimal rational tangents (VMRT) of a uniruled projective manifold at a general point is projectively equivalent to that of a symplectic or an odd-symplectic Grassmannian, the germ of a general minimal…

Algebraic Geometry · Mathematics 2019-01-03 Jun-Muk Hwang , Qifeng Li

For a uniruled projective manifold, we prove that a general rational curve of minimal degree through a general point is uniquely determined by its tangent vector. As applications, among other things we give a new proof, using no Lie theory,…

Algebraic Geometry · Mathematics 2007-05-23 Jun-Muk Hwang , Ngaiming Mok

We classify real families of minimal degree rational curves that cover an embedded rational surface. A corollary is that if the projective closure of a smooth surface is not biregular isomorphic to the projective closure of the unit-sphere,…

Algebraic Geometry · Mathematics 2021-03-09 Niels Lubbes

Among recently introduced new notions in real algebraic geometry is that of regulous functions. Such functions form a foundation for the development of regulous geometry. Several interesting results on regulous varieties and regulous…

Algebraic Geometry · Mathematics 2017-03-17 Wojciech Kucharz , Maciej Zieliński

We determine all of lines in the moduli space $M$ of stable bundles for arbitrary rank and degree. A further application of minimal rational curves is also given in last section.

Algebraic Geometry · Mathematics 2015-05-13 Ngaiming Mok , Xiaotao Sun

We study the family of rational curves on arbitrary smooth hypersurfaces of low degree using tools from analytic number theory.

Algebraic Geometry · Mathematics 2018-03-16 Tim Browning , Pankaj Vishe

Consider a simple algebraic group G of adjoint type, and its wonderful compactification X. We show that X admits a unique family of minimal rational curves, and we explicitly describe the subfamily consisting of curves through a general…

Algebraic Geometry · Mathematics 2015-07-14 Michel Brion , Baohua Fu

In this paper we look for necessary and sufficient conditions for a genus one fibration to have rational curves. We show that a projective variety with log terminal singularities that admits a relatively minimal genus one fibration…

Algebraic Geometry · Mathematics 2019-03-14 Fabrizio Anella

In this paper, we study unirational differential curves and the corresponding differential rational parametrizations. We first investigate basic properties of proper differential rational parametrizations for unirational differential…

Algebraic Geometry · Mathematics 2020-01-27 Lei Fu , Wei Li

We formulate the equivalence problem, in the sense of E. Cartan, for families of minimal rational curves on uniruled projective manifolds. An important invariant of this equivalence problem is the variety of minimal rational tangents. We…

Algebraic Geometry · Mathematics 2009-08-17 Jun-Muk Hwang

We study vector bundles on curves with rational tails and their smoothings and give a sufficient condition for the general fibre to be balanced.

Algebraic Geometry · Mathematics 2022-11-22 Ziv Ran

This paper is concerned with rational curves on real classical groups. Our contributions are three-fold: (i) We determine the structure of quadratic rational curves on real classical groups. As a consequence, we completely classify…

Algebraic Geometry · Mathematics 2024-08-09 Zijia Li , Ke Ye

We construct smooth rational real algebraic varieties of every dimension $\ge$ 4 which admit infinitely many pairwise non-isomorphic real forms.

Algebraic Geometry · Mathematics 2018-07-17 Adrien Dubouloz , Gene Freudenburg , Lucy Moser-Jauslin

Let $X$ be a projective variety with log terminal singularities and vanishing augmented irregularity. In this paper we prove that if $X$ admits a relatively minimal genus one fibration then it does contain a subvariety of codimension one…

Algebraic Geometry · Mathematics 2019-03-14 Fabrizio Anella

All rational parametric curves with prescribed polynomial tangent direction form a vector space. Via tangent directions with rational norm, this includes the important case of rational Pythagorean hodograph curves. We study vector subspaces…

Metric Geometry · Mathematics 2023-01-31 Hans-Peter Schröcker , Zbyněk Šír

We study the behaviour of rational curves tangent to a hypersurface under degenerations of the hypersurface. Working within the framework of logarithmic Gromov-Witten theory, we extend the degeneration formula to the logarithmically…

Algebraic Geometry · Mathematics 2022-10-27 Lawrence Jack Barrott , Navid Nabijou

The variety of minimal rational tangents associated to Hecke curves was used by J.-M.Hwang [8] to prove the simplicity of the tangent bundle on the moduli of vector bundles over a curve. In this paper, we use the tangent maps of the…

Algebraic Geometry · Mathematics 2022-11-07 Insong Choe , George H. Hitching , Jaehyun Hong

A cone structure on a complex manifold $M$ is a closed submanifold $\mathcal C \subset \mathbb P TM$ of the projectivized tangent bundle which is submersive over $M$. A conic connection on $\mathcal C$ specifies a distinguished family of…

Differential Geometry · Mathematics 2020-10-30 Jun-Muk Hwang , Katharina Neusser

This paper deals with rational curves and birational contractions on irreducible holomorphically symplectic manifold. We survey some recent results about minimal rational curves, their deformations, extremal rays associated with these…

Algebraic Geometry · Mathematics 2020-11-18 Ekaterina Amerik , Misha Verbitsky

We construct positive-genus analogues of Welschinger's invariants for many real symplectic manifolds, including the odd-dimensional projective spaces and the renowned quintic threefold. In some cases, our invariants provide lower bounds for…

Symplectic Geometry · Mathematics 2018-02-27 Penka Georgieva , Aleksey Zinger