Chow groups of weighted hypersurfaces

Decomposition of small diagonals and Chow rings of hypersurfaces and Calabi-Yau complete intersections

On one hand, for a general Calabi-Yau complete intersection X, we establish a decomposition, up to rational equivalence, of the small diagonal in X^3, from which we deduce that any decomposable 0-cycle of degree 0 is in fact rationally equivalent to 0, up to torsion. On the other hand, we find a similar decomposition of the smallest diagonal in a higher power of a hypersurface, which provides us an analogous result on the multiplicative structure of its Chow ring.

Chow Rings of Mp_{0,2}(N,d) and Mbar_{0,2}(P^{N-1},d) and Gromov-Witten Invariants of Projective Hypersurfaces of Degree 1 and 2

In this paper, we prove formulas that represent two-pointed Gromov-Witten invariant <O_{h^a}O_{h^b}>_{0,d} of projective hypersurfaces with d=1,2 in terms of Chow ring of Mbar_{0,2}(P^{N-1},d), the moduli spaces of stable maps from genus 0 stable curves to projective space P^{N-1}. Our formulas are based on representation of the intersection number w(O_{h^a}O_{h^b})_{0,d}, which was introduced by Jinzenji, in terms of Chow ring of Mp_{0,2}(N,d), the moduli space of quasi maps from P^1 to P^{N-1} with two marked points. In order to prove our formulas, we use the results on Chow ring of Mbar_{0,…

Prym-Tjurin Constructions on Cubic Hypersurfaces

In this paper, we give a Prym-Tjurin construction for the cohomology and the Chow groups for a cubic hypersurface. On the space of lines meeting a given rational curve, there is the incidence correspondence. This correspondence induces an action on both of the primitive cohomology and the primitive Chow groups. We first show that this action satisfies a quadratic equation. Then the Abel-Jacobi homomorphism induces an isomorphism between the primitive cohomology of the cubic hypersurface and the Prym-Tjurin part of the above action. This also holds for Chow groups with rational coefficients.

Chow rings and decomposition theorems for families of K3 surfaces and Calabi-Yau hypersurfaces

The decomposition theorem for smooth projective morphisms $π:\mathcal{X}\rightarrow B$ says that $Rπ_*\mathbb{Q}$ decomposes as $\oplus R^iπ_*\mathbb{Q}[-i]$. We describe simple examples where it is not possible to have such a decomposition compatible with cup-product, even after restriction to Zariski dense open sets of $B$. We prove however that this is always possible for families of $K3$ surfaces (after shrinking the base), and show how this result relates to a result by Beauville and the author on the Chow ring of $K3$ surfaces $S$. We give two proofs of this result, the second one involv…

Tropical Chow Hypersurfaces

Given a projective variety $X$ of codimension $k+1$ in $\mathbb{P}^n$ the Chow hypersurface $Z_X$ is the hypersurface of the Grassmannian $\operatorname{Gr}(k, n)$ parametrizing projective linear spaces that intersect $X$. We introduce the tropical Chow hypersurface $\operatorname{Trop}(Z_X)$. This object only depends on the tropical variety $\operatorname{Trop}(X)$ and we provide an explicit way to obtain $\operatorname{Trop}(Z_X)$ from $\operatorname{Trop}(X)$. We also give a geometric description of $\operatorname{Trop}(Z_X)$. We conjecture that, as in the classical case, $\operatorname{Tro…

Droites sur les hypersurfaces cubiques

Over any complex cubic hypersurface of dimension at least 2, the Chow group of 1-dimensional cycles is spanned by the lines lying on the hypersurface. The smooth case has already been given several other proofs. -- On montre que sur toute hypersurface cubique complexe de dimension au moins 2, le groupe de Chow des cycles de dimension 1 est engendré par les droites. Le cas lisse est un théorème connu. La démonstration ici donnée repose sur un résultat sur les surfaces géométriquement rationnelles sur un corps quelconque (1983), obtenu via la K-théorie algébrique.

关于完全交集的Chow环的问题

Questions on the Chow ring of complete intersections

本文探讨了Calabi-Yau超曲面的Chow环问题，证明了部分结果，并提出了关于MCK分解的猜想。

扭曲Milnor超曲面的Motivic莱夫谢茨定理

Motivic Lefschetz theorem for twisted Milnor hypersurfaces

本研究针对Milnor超曲面内扭曲形式的光滑超平面截面，证明其Grothendieck-Chow motive可分解为相关循环代数的Severi-Brauer簇与极大交换子域的motive平移拷贝的直和，证明依赖于Galois作用在等变Chow群上的非平凡性。

加权爆破的整 Chow 环

The integral Chow ring of weighted blow-ups

该研究给出加权爆破的整 Chow 环计算公式，同时得到加权射影栈丛的整 Chow 环、加权爆破的 Gysin 同态公式与分裂原理的推广，并在附录中算出加权爆破的陈类。

弦Chow环与加权爆破

Stringy Chow rings and weighted blow ups

本文在非代数闭基域上计算形如[X/G]的一般Deligne-Mumford栈的弦Chow环，并专门研究光滑簇沿光滑中心加权爆破的弦Chow环及其有限生成性质。

A model for the orbifold Chow ring of weighted projective spaces

We construct an isomorphism of graded Frobenius algebras between the orbifold Chow ring of weighted projective spaces and graded algebras of groups of roots of the unity.

Hypersurfaces quartiques de dimension 3 : non rationalité stable

Inspirés par un argument de C. Voisin, nous montrons l'existence d'hypersurfaces quartiques lisses dans ${\bf P}^4_{\mathbb C}$ qui ne sont pas stablement rationnelles, plus précisément dont le groupe de Chow de degré zéro n'est pas universellement égal à $\mathbb Z$. --- There are (many) smooth quartic hypersurfaces in ${\bf P}^4_{\mathbb C}$ which are not stably rational. More precisely, their degree zero Chow group is not universally equal to $\mathbb Z$. The proof uses a variation of a specialisation method due to C. Voisin.

曲线的对数Hilbert方案作为加权吹胀及其整环Chow环

Logarithmic Hilbert schemes of curves as weighted blow-ups and their integral Chow rings

本文研究了曲线的对数Hilbert方案作为加权吹胀的结构，并计算了其整环Chow环，利用了加权吹胀的Chow环公式和Castelnuovo准则的加权版本，恢复了对数Hilbert方案为堆栈的结果。

On the universal $\mathrm{CH}_0$ group of cubic threefolds in positive characteristic

We adapt for algebraically closed fields $k$ of characteristic greater than $2$ two results of Voisin, on the decomposition of the diagonal of a smooth cubic hypersurface $X$ of dimension $3$ over $\mathbb C$, namely: the equivalence between Chow-theoretic and cohomological decompositions of the diagonal of those hypersurfaces and the fact that the algebraicity (with $\mathbb Z_2$-coefficients) of the minimal class $θ^4/4!$ of the intermediate jacobian $J(X)$ of $X$ implies the Chow-theoretic decomposition of the diagonal of $X$. Using the second result, the Tate conjecture for divisors on sur…

Hodge-type conjecture for higher Chow groups

Let X be a smooth quasi-projective variety over the algebraic closure of the rational number field. We show that the cycle map of the higher Chow group to Deligne cohomology is injective and the higher Hodge cycles are generated by the image of the cycle map as conjectured by Beilinson and Jannsen, if the cycle map to Deligne cohomology is injective and the Hodge conjecture is true for certain smooth projective varieties over the algebraic closure of the rational number field. We also verify the conjecture on the surjectivity in the case of the complement of a union of general hypersurfaces in…

Motives of hypersurfaces of very small degree

We study the Chow motive (with rational coefficients) of a hypersurface X in the projective space by using the variety F(X) of l-dimensional planes contained in X. If the degree of X is sufficiently small we show that the primitive part of the motive of X is the tensor product of a direct summand in the motive of a suitable complete intersection in F(X) and the l-th twist Q(-l) of the Lefschetz motive.

On toric Calabi-Yau hypersurfaces fibered by weighted K3 hypersurfaces

In response to a question of Reid, we find all anti-canonical Calabi-Yau hypersurfaces $X$ in toric weighted projective bundles over the projective line where the general fiber is a weighted K3 hypersurface. This gives a direct generalization of Reid's discovery of the 95 families of weighted K3 hypersurfaces. We also treat the case where $X$ is fibered over the plane with general fiber a genus one curve in a weighted projective plane.

Segre行列式

The Segre Determinant

本文研究Segre行列式，计算其在不同坐标系下的形式，并证明其代表Grassmannian中通用的torus轨道的Chow-Lam形式，同时探讨其在代数视觉和Grassmannian Chow商中的应用。

关于某些完全交的Chow环中超平面类乘积的注记

A remark on the product by the hyperplane class in the Chow ring of some complete intersections

该研究将光滑超曲面上超平面类乘积在同调平凡有理闭链上为零的经典结果，推广至某些完全交的Chow环情形。

$\boldsymbol{\bar{\rm M}_{1,n}}$的穿墙整Chow环

Wall-crossing integral Chow rings of $\overline{\mathcal M}_{1,n}$

本文通过归纳计算Smyth提出的替代紧化的整Chow环，得到了$n=3,4$时$\bar{\text{M}}_{1,n}$的整Chow环，并指出$n\leq6$时该栈可由简单栈经加权胀缩得到。

Nonvanishing of External Products for Higher Chow Groups

Consider an external product of a higher cycle and a usual cycle which is algebraically equivalent to zero. Assume there exists an algebraically closed subfield k such that the higher cycle and its ambient variety are defined over k, but the image of the usual cycle by the Abel-Jacobi map is not. Then we prove that the external product is nonzero if the image of the higher cycle by the cycle map to the reduced Deligne cohomology does not vanish. We also give examples of indecomposable higher cycles on even dimensional hypersurfaces of degree at least four in a projective space such that the la…

Smooth weighted hypersurfaces that are not stably rational

We prove the failure of stable rationality for many smooth well formed weighted hypersurfaces of dimension at least 3. It is in particular proved that a very general smooth well formed Fano weighted hypersurface of index one is not stably rational.

Chow groups of the moduli spaces of weighted pointed stable curves of genus zero

The moduli space $\bar{M}_A$ of weighted pointed stable curves of genus zero is stratified according to the degeneration types of such curves. We show that the homology groups of the moduli space $\bar{M}_A$ are generated by the strata of $\bar{M}_A$ and give all additive relations between them. We also observe that the Chow groups $A_i \bar{M}_A$ and the homology groups $H_{2i} \bar{M}_A$ are isomorphic. This generalizes Kontsevich-Manin's and Losev-Manin's theorems to arbitrary weight data $A$.

Halphen Pencils on Weighted Fano Threefold Hypersurfaces

We classify all pencils on a general weighted hypersurface in $\mathbb{P}(1,a_{1},a_{2},a_{3},a_{4})$ of degree $\sum_{i=1}^{4}a_{i}$ whose general members are surfaces of Kodaira dimension zero.

Elliptic structures on weighted three-dimensional Fano hypersurfaces

We classify birational maps into elliptic fibrations of a general quasismooth hypersurface in $\mathbb{P}(1,a_{1},a_{2},a_{3},a_{4})$ of degree $\sum_{i=1}^{4}a_{i}$ that has terminal singularities.

Gauss-Manin systems of wild regular functions: Givental-Hori-Vafa models of smooth hypersurfaces in weighted projective spaces as an example

We study Gauss-Manin systems of non tame Laurent polynomial functions. We focuse on Hori-Vafa models, which are the expected mirror partners of the small quantum cohomology of smooth hypersurfaces in weighted projective spaces.

Isomorphism among families of weighted K3 hypersurfaces

Some of the 95 families of weighted K3 hypersurfaces have been known to have the isometric lattice polarizations. It is shown that weighted K3 hypersurfaces in such families are to one-to-one correspond by explicitly constructing the monomial birational morphisms among the weighted projective spaces. All the weight systems having the isometric Picard lattices commonly possess an anticanonical sublinear system, being confirmed that the Picard lattice of the sublinear system we obtained is the same as those of the complete linear systems.

Fano hypersurfaces in weighted projective 4-spaces

We determine the complete list of anticanonically embedded quasi smooth log Fano 3-folds in weighted projective 4-spaces. This implies that the Reid-Fletcher list of 95 types of anticanonically embedded quasi smooth terminal Fano threefolds in weighted projective 4-spaces is complete. We also prove that there are only finitely many families of quasi smooth Calabi-Yau hypersurfaces in weighted projective spaces of any given dimension.

立方超曲面的奇点与射影化切丛的超平面截面

Singularity of cubic hypersurfaces and hyperplane sections of projectivized tangent bundle of projective space

研究立方超曲面的奇点性质，并通过线性代数方法描述射影空间射影化切丛的超平面截面，扩展了Mazouni-Nagaraj的高维结果。

素数幂阶的加权超曲面的自同构

Automorphisms of prime power order of weighted hypersurfaces

研究加权射影空间中准光滑超曲面的自同构，扩展经典结果至加权情形，推导素数幂阶自同构的有效判据和素数阶上限。

On the universal $CH_0$ group of cubic hypersurfaces

We study the existence of a Chow-theoretic decomposition of the diagonal of a smooth cubic hypersurface, or equivalently, the universal triviality of its ${\rm CH}_0$-group. We prove that for odd dimensional cubic hypersurfaces or for cubic fourfolds, this is equivalent to the existence of a cohomological decomposition of the diagonal, and we translate geometrically this last condition. For cubic threefolds $X$, this turns out to be equivalent to the algebraicity of the minimal class $θ^4/4!$ of the intermediate Jacobian $J(X)$. In dimension $4$, we show that a special cubic fourfold with disc…

加权射影超曲面的自同构

Automorphisms of weighted projective hypersurfaces

本文研究拟光滑复加权射影超曲面的自同构群，证明自同构在多数情形下可延拓到外围空间，给出线性自同构群有限的刻画及一致上界，并描述了给定权和次数的通用超曲面的自同构。

双有理超刚性Fano三维加权超曲面的K-稳定性

K-stability of birationally superrigid Fano 3-fold weighted hypersurfaces

该研究证明指数为1的拟光滑Fano三维加权超曲面的α不变量≥1/2，结合已有双有理超刚性与K-稳定性的关系结论，推导出这类双有理超刚性曲面的K-稳定性。

有理加权射影超曲面

Rational weighted projective hypersurfaces

本文研究了加权射影超曲面的有理性，引入了高次加权超曲面的有理性构造，提供了任意域上的新有理例子，并肯定回答了T. Okada关于所有维数$n \geq 6$下存在非常一般端Fano有理加权超曲面的问题。

加权射影空间乘积中超曲面的双有理几何

Birational geometry of hypersurfaces in products of weighted projective spaces

本研究扩展了加权射影空间乘积中超曲面的双有理几何理论，确定了Mori梦想空间情形下的所有相关锥、双有理模型及Cox环，并证明了终端Calabi-Yau超曲面的Kawamata-Morrison锥猜想之双有理形式。

Weighted Chern-Mather classes and Milnor classes of hypersurfaces

We introduce a class extending the notion of Chern-Mather class to possibly nonreduced schemes, and use it to express the difference between Schwartz-MacPherson's Chern class and the class of the virtual tangent bundle of a singular hypersurface of a nonsingular variety. Applications include constraints on the possible singularities of a hypersurface and on contacts of nonsingular hypersurfaces, and multiplicity computations.

Isotropic and Coisotropic Subvarieties of Grassmannians

We generalize the notion of coisotropic hypersurfaces to subvarieties of Grassmannians having arbitrary codimension. To every projective variety X, Gel'fand, Kapranov and Zelevinsky associate a series of coisotropic hypersurfaces in different Grassmannians. These include the Chow form and the Hurwitz form of X. Gel'fand, Kapranov and Zelevinsky characterized coisotropic hypersurfaces by a rank one condition on conormal spaces, which we use as the starting point for our generalization. We also study the dual notion of isotropic varieties by imposing rank one conditions on tangent spaces instead…

加权射影空间中非常一般超曲面的代数双曲性

Algebraic hyperbolicity of very general hypersurfaces in weighted projective spaces

本文研究加权射影空间中非常一般超曲面的代数双曲性，通过给出丰沛线丛倍数 $m$ 的界，证明了相应零点轨迹具有代数双曲性。

K3 型加权四维 Fano 超曲面

Weighted four-dimensional Fano hypersurfaces of K3 type

本文证明在奇点轨迹维数至多为一的假设下，K3 型加权 Fano 四维超曲面族仅有有限多个，并给出完整列表及有理性和奇点分析。

Nakai猜想对于孤立的齐次超曲面奇点

Nakai conjectures for isolated weighted homogeneous hypersurface singularities

本文验证了Nakai猜想在孤立齐次超曲面奇点情况下的成立，探讨微分算子与奇点检测的关系。

通过plt标志和凸几何研究Fano加权超曲面的K稳定性

K-stability of Fano weighted hypersurfaces via plt flags and convex geometry

本文通过结合birational和凸几何技术，证明了特定条件下的加权Fano超曲面的K稳定性，并构造了K不稳定的例子。

K-模空间的墙交叉：某些加权投影超曲面的家族

Wall-crossing for K-moduli spaces of certain families of weighted projective hypersurfaces

本文研究了特定加权投影超曲面的K-模空间，并通过显式分析展示了K-模空间的墙交叉现象，揭示了其与GIT变化的关系及最后的分式收缩。

计算二次空间曲线的 Chow 簇

Computing the Chow variety of quadratic space curves

本文研究三维空间直线 Grassmannian 中二次曲面的余迷向超曲面子簇，按 GKZ 理论将其分解为三类轨迹，并计算相应理想。

加权射影三维空间中超曲面的对称微分

Symmetric differentials on weighted hypersurfaces

本文研究加权射影三维空间中超曲面的对称微分，证明光滑及拟光滑超曲面的消失性质，并构造具有大余切丛的奇异例子，结合同时消解得到对称多重亏格从零跳跃至三次增长的形变等价曲面。

Simple cyclic covers of the plane and Seshadri constants of some general hypersurfaces in weighted projective space

Let $X$ be a general hypersurface of degree $md$ in the weighted projective space with weights $1,1,1,m$ for some for $d\geq 2$ and $m\geq 3$. We prove that the Seshadri constant of the ample generator of the Néron-Severi space at a general point $x\in X$ lies in the interval $\left[\sqrt{d}- \frac d m, \sqrt{d}\right]$ and thus approaches the possibly irrational number $\sqrt d$ as $m$ grows.

加权射影空间上有限域上超曲面的有理点最大数

Maximum number of rational points on hypersurfaces in weighted projective spaces over finite fields

本文在第二重量为1的条件下，证明了加权射影空间上有限域中超曲面有理点最大数的猜想，扩展了之前在二维情况下的结果。

通过奇点范畴的（加权）超曲面的范畴Torelli定理

Categorical Torelli theorem for (weighted) hypersurfaces via singularity category

本文利用完备仿射锥的奇点范畴，在数值条件下统一证明了Fano及一般型（加权）超曲面的范畴Torelli定理，并通过形式等价恢复方程结构。

The generalized Hodge and Bloch conjectures are equivalent for general complete intersections

Let $X$ be a smooth complex projective variety with trivial Chow groups. (By trivial, we mean that the cycle class is injective.) We show (assuming the Lefschetz standard conjecture) that if the vanishing cohomology of a general complete intersection $Y$ of ample hypersurfaces in $X$ has geometric coniveau $\geq c$, then the Chow groups of cycles of dimension $\leq c-1$ of $Y$ are trivial. The generalized Bloch conjecture for $Y$ is this statement with "geometric coniveau" replaced by "Hodge coniveau".

Hypersurface exceptional singularities

This paper studies hypersurface exceptional singularities in $\mathbb C^n$ defined by non-degenerate function. For each canonical hypersurface singularity, there exists a weighted homogeneous singularity such that the former is exceptional if and only if the latter is exceptional. So we study the weighted homogeneous case and prove that the number of weights of weighted homogeneous exceptional singularities are finite. Then we determine all exceptional singularities of the Brieskorn type of dimension 3.

Stable rationality of orbifold Fano threefold hypersurfaces

We determine the rationality of very general quasismooth Fano 3-fold weighted hypersurfaces completely and determine the stable rationality of them except for cubic 3-folds. More precisely we prove that (i) very general Fano 3-fold weighted hypersurfaces of index 1 or 2 are not stably rational except possibly for the cubic threefolds, (ii) among the 27 families of Fano 3-fold weighted hypersurfaces of index greater than 2, very general members of specific 7 families are not stably rational and the remaining 20 families consists of rational varieties.

加权超曲面Fano三维簇的自同构群与柱性

Automorphism groups and cylindricity of weighted hypersurface Fano threefolds

本文针对拟光滑终端加权超曲面Fano三维簇剩余的20个形变族，研究其每个成员的柱性与完全自同构群，并探讨这些族的形式的柱性，补充了相关分类研究的空白。

Euler characteristics of homogeneous and weighted-homogeneous hypersurfaces

Let $k$ be a field and let $\text{GW}(k)$ be the Grothendieck-Witt ring of virtual non-degenerate symmetric bilinear forms over $k$. We develop methods for computing the quadratic Euler characteristic $χ(X/k)\in \text{GW}(k)$ for $X$ a smooth hypersurface in a projective space or a weighted projective space. We raise the question of a quadratic refinement of classical conductor formulas and find such a formula for the degeneration of a smooth hypersurface $X$ in $\mathbb{P}^{n+1}$ to the cone over a smooth hyperplane section of $X$; we also find a similar formula in the weighted homogeneous ca…

Mirror fibrations and root stacks of weighted projective spaces

We show that the orbifold Chow ring of a root stack over a well-formed weighted projective space can be naturally seen as the Jacobian algebra of a function on a singular variety given by a partial compactification of its Ginzburg-Landau model.

Four-dimensional projective orbifold hypersurfaces

We classify four-dimensional quasismooth weighted hypersurfaces with small canonical class, and verify a conjecture of Johnson and Kollar on infinite series of quasismooth hypersurfaces with anticanonical hyperplane section in the case of fourfolds. By considering the quotient singularities that arise, we classify those weighted hypersurfaces that are canonical, Calabi-Yau, and Fano fourfolds. We also consider other classes of hypersurfaces, including Fano hypersurfaces of index greater than 1 in dimensions 3 and 4.