Hermite簇的正交表

The geometry of Hermitian self-orthogonal codes

We prove that if $n >k^2$ then a $k$-dimensional linear code of length $n$ over ${\mathbb F}_{q^2}$ has a truncation which is linearly equivalent to a Hermitian self-orthogonal linear code. In the contrary case we prove that truncations of linear codes to codes equivalent to Hermitian self-orthogonal linear codes occur when the columns of a generator matrix of the code do not impose independent conditions on the space of Hermitian forms. In the case that there are more than $n$ common zeros to the set of Hermitian forms which are zero on the columns of a generator matrix of the code, the addit…

$\mathbb{P}^{4}(\mathbb{F}_q)$中二次和非退化厄米簇的2次形式定义的码

Codes defined by forms of degree 2 on quadric and non-degenerate hermitian varieties in $\mathbb{P}^{4}(\mathbb{F}_q)$}

本文研究了G. Lachaud关于$\mathcal{X} \subset {\mathbb{P}}^4(\mathbb{F}_q)$是秩为（$\mathcal{X}$）= 3，4，5的二次曲面或非退化埃尔米特簇.我们给出了$\mathcal{X}$的二次截面的点数%$# \mathcal{X}_{Z(\mathcal{Q})}(\mathbb{F}_{q})$的一些界，这些界是最好的，并且表明定义在非退化二次曲面上的码优于定义在退化二次曲面上的码。我们还展示了最小重量码字的几何结构，并估计了这些码的第二重量。对于非退化厄米簇$\mathcal{X}$，我们列出了前五个权重和相应的码字。文章最后以两个结论结束。一个是关于非奇异厄米簇$\mathcal{X} \subset {\mathbb{P}}^4(\mathbb{F}_q)$上$h$阶泛函码的最小距离。关于非奇异厄米簇$\mathcal{X} \subset {\mathbb{P}}^N(\mathbb{F}_q)$上二阶泛函码前五个权码字分布的第二个猜想。

Symmetric Dellac configurations and symplectic/orthogonal flag varieties

The goal of this paper is to study the link between the topology of the degenerate flag varieties and combinatorics of the Dellac configurations. We define three new classes of algebraic varieties closely related to the degenerate flag varieties of types A and C. The construction is based on the quiver Grassmannian realization of the degenerate flag varieties and odd symplectic and odd and even orthogonal groups. We study basic properties of our varieties; in particular, we construct cellular decomposition in all the three cases above (as well as in the case of even symplectic group). We also …

Determining when a truncated generalised Reed-Solomon code is Hermitian self-orthogonal

We prove that there is a Hermitian self-orthogonal $k$-dimensional truncated generalised Reed-Solomon code of length $n \leqslant q^2$ over ${\mathbb F}_{q^2}$ if and only if there is a polynomial $g \in {\mathbb F}_{q^2}$ of degree at most $(q-k)q-1$ such that $g+g^q$ has $q^2-n$ distinct zeros. This allows us to determine the smallest $n$ for which there is a Hermitian self-orthogonal $k$-dimensional truncated generalised Reed-Solomon code of length $n$ over ${\mathbb F}_{q^2}$, verifying a conjecture of Grassl and Rötteler. We also provide examples of Hermitian self-orthogonal $k$-dimension…

正交旗簇的Schubert多项式和Arakelov理论

Schubert polynomials and Arakelov theory of orthogonal flag varieties

本文提出了一种组合显式Schubert多项式理论，它表示正交旗簇的上同调环的Borel表示中的Schubert类.我们使用这些多项式来描述这些空间上的算术舒伯特演算。给出了自然算术相交数的计算方法，并证明了它们都是有理数。

On torus quotients of Schubert varieties in orthogonal Grassmannian-II

Let $G=SO(8n+4,\mathbb{C})$ ($n\ge 1$). Let $B$ be a Borel subgroup of $G$ containing a maximal torus $T$ of $G.$ Let $P (\supset B)$ denote the maximal parabolic subgroup of $G$ corresponding to the simple root $α_{4n+2}$. In this article, we prove projective normality of the GIT quotients of certain Schubert varieties in the orthogonal Grassmannian $G/P$ with respect to the descent of a suitable $T$-linearized very ample line bundle.

正交Grassmannian中Schubert簇切锥的初始理想

Initial ideals of tangent cones to Schubert varieties in orthogonal Grassmannians

我们计算的初始理想，关于某些方便地选择的条款的订单，切锥的理想在环面不动点的舒伯特品种在正交格拉斯曼。初始理想是无平方的单项理想，因此是单纯复形的Stanley-Reisner面环。我们描述了这些复合物。这些复合物的最大面编码某些不相交的晶格路径集。

正交Grassmannian中Richardson簇的切锥的初始理想的有界RSK对应

Initial ideals of tangent cones to Richardson varieties in the Orthogonal Grassmannian via a Orthogonal-Bounded-RSK-Correspondence

正交格拉斯曼中的Richardson簇$X_\ga^\gc$被定义为正交格拉斯曼中的舒伯特簇$X^\gc$与其中的相反舒伯特簇$X_\ga$的交集。给出了$X_\ga^\gc$的任意$T$ -不动点处切锥理想的初始理想（关于某些方便选择的项阶）的显式描述，从而推广了Raghavan-Upadhyay \cite{Ra-Up2}的一个结果.我们的证明是基于广义的Robinson-Schensted-Knuth（RSK）对应，我们称之为正交有界RSK（OBRSK）。OBRSK对应将给出由切锥的理想的初始理想（如上所述）定义的一组单项式和“标准单项式基”之间的保度双射。Kreiman在\cite{Kr-bkrs}中对普通Grassmannian中的Richardson变种做了类似的工作。

典型群的若干单模与正交几何和埃尔米特几何的$p$-秩

Some simple modules for classical groups and $p$-ranks of orthogonal and Hermitian geometries

该研究确定了典型群部分Weyl模的单合成因子特征标与子模格，其结果可应用于有限几何关联系统研究，通过单模维数得到关联系统的$p$-秩。

低维中秩 $n$ Hermitian 簇和超曲面产生的函数码

Functional codes arising from rank $n$ Hermitian varieties and hypersurfaces in low dimensions

研究秩 $n$ 退化 Hermitian 簇 $P\\\mathcal{U}_{n-1}$ 在 $\\mathbb{P}^n(\\mathbb{F}_{q^2})$ 上的函数码 $C_d(\\mathcal{X})$，当 $d\\\leq q$ 时，通过建立交点数的上界，确定了 $n=2,3,4$ 时码的参数并刻画了达到最小距离的超曲面。

如何扩展自正交码

How to Expand a Self-orthogonal Code

本文提出了一种扩展自正交码的方法，保持其正交性质，并给出了适用于不同参数条件的扩展算法。

On the geometry of the Hermitian Veronese curve and its quasi-Hermitian surfaces

The complete classification of the orbits on subspaces under the action of the projective stabiliser of (classical) algebraic varieties is a challenging task, and few classifications are complete. We focus on a particular action of $\PGL(2,q^2)$ (and $\PSL(2,q^2)$) arising from the Hermitian Veronese curve in $\PG(3, q^2)$, a maximal rational curve embedded on a smooth Hermitian surface with some fascinating properties. The study of its orbits leads to a new construction of quasi-Hermitian surfaces: sets of points with the same combinatorial and geometric properties as a non-degenerate Hermiti…

Mather classes of Schubert varieties via small resolutions

We express a Schubert expansion of the Chern-Mather class for Schubert varieties in the even orthogonal Grassmannian via integrals involving Pfaffians and pushforward of the small resolutions in the sense of Intersection Cohomology (IH) constructed by Sankaran and Vanchinathan, instead of the Nash blowup. The equivariant localization is employed to show the way of computing the integral. As a byproduct, we present the computations. For analogy and the completion of the method in ordinary Grassmannians, we also suggest Kazhdan-Lusztig classes associated to Schubert varieties in the Lagrangian a…