arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1304.1256math.COmath.AG
收藏

一个关于Severi度的组合分析

A combinatorial analysis of Severi degrees

Fu Liu

摘要:

在Brugallé和Mikhalkin的基础上,Fomin和Mikhalkin给出了利用长边图计算经典Severi度$N^{d, δ}$的公式.在2012年,Block、Colley和Kennedy考虑了Fomin-Mikhalkin公式中出现的与长边图相关的特殊函数的对数版本,并证明它是线性的。他们已经证明了他们的猜想。同时,受他们猜想的启发,我们考虑了一个与长边图相关的特殊的多元函数,推广了他们的函数。本文的主要结果是我们定义的多元函数总是线性的。本文结果的一个特例给出了Block-Colley-Kennedy猜想的一个独立证明。我们的线性结果的第一个应用是,通过将其应用于经典的塞维度,我们恢复二次的$Q^{d, δ}$和约束$δ$的阈值多项式的$N^{d, δ}.$接下来,在联合工作与Osserman,我们适用于一个特殊的家庭的复曲面的线性结果,并获得普遍的多项式结果具有连接到Göttsche-Yau-Zaslow公式。因此,我们给出了Göttsche-Yau-Zaslow公式中出现的两个未知幂级数$B_1(q)$和$B_2(q)$的组合公式.我们的线性结果的证明是完全组合的。我们定义了$τ$ -图,它推广了长边图,并定义了一类密切相关的组合对象,我们称之为$(τ, n)$ -词.通过引入高度函数和不可约化的概念,我们描述了如何将某些家庭的$(τ, n)$ -字分解成不可约的话,这导致了预期的结果。

英文摘要:

Based on results by Brugallé and Mikhalkin, Fomin and Mikhalkin give formulas for computing classical Severi degrees $N^{d, δ}$ using long-edge graphs. In 2012, Block, Colley and Kennedy considered the logarithmic version of a special function associated to long-edge graphs appeared in Fomin-Mikhalkin's formula, and conjectured it to be linear. They have since proved their conjecture. At the same time, motivated by their conjecture, we consider a special multivariate function associated to long-edge graphs that generalizes their function. The main result of this paper is that the multivariate function we define is always linear. A special case of our result gives an independent proof of Block-Colley-Kennedy's conjecture. The first application of our linearity result is that by applying it to classical Severi degrees, we recover quadraticity of $Q^{d, δ}$ and a bound $δ$ for the threshold of polynomiality of $N^{d, δ}.$ Next, in joint work with Osserman, we apply the linearity result to a special family of toric surfaces and obtain universal polynomial results having connections to the Göttsche-Yau-Zaslow formula. As a result, we provide combinatorial formulas for the two unidentified power series $B_1(q)$ and $B_2(q)$ appearing in the Göttsche-Yau-Zaslow formula. The proof of our linearity result is completely combinatorial. We define $τ$-graphs which generalize long-edge graphs, and a closely related family of combinatorial objects we call $(τ, n)$-words. By introducing height functions and a concept of irreducibility, we describe ways to decompose certain families of $(τ, n)$-words into irreducible words, which leads to the desired results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑