Asymptotic Np property of rational surfaces

Asymptotic behaviour of rational curves

We investigate the asympotic behaviour of the moduli space of morphisms from the rational curve to a given variety when the degree becomes large. One of the crucial tools is the homogeneous coordinate ring of the variey. First we explain in details what happens in the toric case. Then we examine the general case.

加权射影空间中的有理正规曲线

Rational Normal Curves in Weighted Projective Space

该研究将有理正规曲线的经典同调理论推广至加权射影空间，建立了行列式性以及二次生成与 Koszul 性质的非标准形式。

Some results on rational surfaces and Fano varieties

The goal of this article is to study the equations and syzygies of embeddings of rational surfaces and certain Fano varieties. Given a rational surface X and an ample and base-point-free line bundle L on X, we give an optimal numerical criterion for L to satisfy property Np. This criterion turns out to be a characterization of property Np if X is anticanonical. We also prove syzygy results for adjunction bundles and a Reider type theorem for higher syzygies. For certain Fano varieties we also prove results on very ampleness and higher syzygies.

Kawamata-Viehweg Vanishing on Rational Surfaces in Positive Characteristic

We prove that the Kawamata-Viehweg vanishing theorem holds on rational surfaces in positive characteristic by means of the lifting property to W_2(k) of certain log pairs on smooth rational surfaces. As a corollary, the Kawamata-Viehweg vanishing theorem holds on log del Pezzo surfaces in positive characteristic.

On a new class of rational cuspidal plane curves with two cusps

In this paper, we consider rational cuspidal plane curves having exactly two cusps whose complements have logarithmic Kodaira dimension two. We classify such curves with the property that the strict transforms of them via the minimal embedded resolution of the cusps have maximal self-intersection number.

随机 Fano 超曲面上有理点的分布

Distribution of rational points on random Fano hypersurfaces

本文证明了随机 Fano 超曲面上有理点平均数量的渐近公式，以及容许 adelic 点的超曲面数量的渐近公式。

Asymptotic slopes of the Aubin-Yau functional and calculation of the Donaldson-Futaki invariant

We derive an explicit formula for the asymptotic slope of the Aubin-Yau functional along a Bergman geodesic on a surface of complex dimension 2, extending the work of Phong-Sturm on Riemann surfaces. This is equivalent to an explicit calculation of the Donaldson-Futaki invariant of a test configuration. The slope is given as a rational linear combination of period integrals of rational functions that sum to a rational number. The result gives a way to check directly whether a two dimensional projective variety is K-stable.

Ulrich 丛的 Koszul 性质与 Del Pezzo 曲面上稳定丛模空间的有理性

Koszul property of Ulrich bundles and rationality of moduli spaces of stable bundles on Del Pezzo surfaces

本文研究 Del Pezzo 曲面上 Ulrich 丛的 Koszul 性质与迭代 syzygy 丛的斜率半稳定性，并证明无穷多个稳定丛模空间具有有理性，为 Costa 和 Miró-Roig 猜想提供新证据。

Varieties of minimal rational tangents on double covers of projective space

Let $ϕ: X \to \mathbb P^n$ be a double cover branched along a smooth hypersurface of degree $2m, 2 \leq m \leq n-1$. We study the varieties of minimal rational tangents $\mathcal C_x \subset \mathbb P T_x(X)$ at a general point $x$ of $X$. We describe the homogeneous ideal of $\mathcal C_x$ and show that the projective isomorphism type of $\mathcal C_x$ varies in a maximal way as $x$ varies over general points of $X$. Our description of the ideal of $\mathbb C_x$ implies a certain rigidity property of the covering morphism $ϕ$. As an application of this rigidity, we show that any finite morphi…

On Orevkov's rational cuspidal plane curves

In this note, we consider rational cuspidal plane curves having exactly one cusp whose complements have logarithmic Kodaira dimension two. We classify such curves with the property that the strict transforms of them via the minimal embedded resolution of the cusp have the maximal self-intersection number. We show that the curves given by the classification coincide with those constructed by Orevkov.

On the Number of Rational Points of Jacobians over Finite Fields

In this article we prove lower and upper bounds for class numbers of algebraic curves defined over finite fields. These bounds turn out to be better than most of the previously known bounds obtained using combinatorics. The methods used in the proof are essentially those from the explicit asymptotic theory of global fields. We thus provide a concrete application of effective results from the asymptotic theory of global fields and their zeta-functions.

数域上 Hirzebruch-Kleinschmidt 簇的有理点计数

Counting rational points on Hirzebruch-Kleinschmidt varieties over number fields

本文研究了数域上 Picard 秩为 2 的光滑射影分裂环面簇在 Arakelov 高度下的有理点渐近增长，证明其可分解为有限个不相交子簇并给出显式渐近公式，同时提供了包含 Hirzebruch 曲面的实例。

Rational points of rationally simply connected varieties over global function fields

A complex projective manifold is rationally connected, resp. rationally simply connected, if finite subsets are connected by a rational curve, resp. the spaces parameterizing these connecting rational curves are themselves rationally connected. We prove that a projective scheme over a global function field with vanishing "elementary obstruction" has a rational point if it deforms to a rationally simply connected variety in characteristic 0. This gives new, uniform proofs over these fields of the Period-Index Theorem, the quasi-split case of Serre's "Conjecture II", and Lang's $C_2$ property.

Rational Points on Weighted projective Spaces

In this paper,we count the rational points on the weighted projective spaces defined over number fields w.r.t. ``size''. An asymptotic formula which generalizes the result of Schanuel's ``Heights in number fields'' is obtained. Furthermore, we count also the rational points on the product of weighted projective spaces.

Multiple Mixing for adele groups and rational points

We prove an asymptotic formula for the number of rational points of bounded height on projective equivariant compactifications of $H\G$, where $H$ is a connected simple algebraic group embedded diagonally into $G := H^n$.