arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0901.2457math.AGmath.AC
收藏

合合丛的稳定性和无阻性

Stability and Unobstructedness of Syzygy Bundles

L. Costa, P. Macias Marques, R. M. Miró-Roig

摘要:

判定定义为一般满态$\xymatrix{ϕ:\cO(-d_1)\oplus...\oplus\cO(-d_n)\ar[r] &\cO}$的核的$\PP^N$上的合丛$E_{d_1,..., d_n}$是否(半)稳定是代数几何中一个长期存在的问题.在本说明中,我们将注意力限制在与$d$相同度的$n$泛型形式$f_1,...,f_n\in K[X_0,X_1,..., X_N]$相关联的$\PP^N$上的合束$E_{d,n}$的情况。我们的第一个目标是证明$E_{d,n}$是稳定的,如果$N+1\le n\le\tbinom{d+2}{2}+N-2$。这个界一般地改进了G. Hein,见\cite{B},附录A。在文章的最后一部分,我们研究了含合合丛的$\PP^N$上的稳定秩$n-1$向量丛的模空间。我们证明了如果$N+1\le n\le\tbinom{d+2}{2}+N-2$和$N\ne 3$,那么合合丛$E_{d,n}$是通畅的,并且它属于维数$n\tbinom{d+N}{N}-n^2$的一般光滑不可约分支,如果$N \geq 4$,和$n\tbinom{d+2}{2}+n\tbinom{d-1}{2}-n^2$,如果N=2。

英文摘要:

It is a longstanding problem in Algebraic Geometry to determine whether the syzygy bundle $E_{d_1,..., d_n}$ on $\PP^N$ defined as the kernel of a general epimorphism $\xymatrix{ϕ:\cO(-d_1)\oplus...\oplus\cO(-d_n)\ar[r] &\cO}$ is (semi)stable. In this note, we restrict our attention to the case of syzygy bundles $E_{d,n}$ on $\PP^N$ associated to $n$ generic forms $f_1,...,f_n\in K[X_0,X_1,..., X_N]$ of the same degree $d$. Our first goal is to prove that $E_{d,n}$ is stable if $N+1\le n\le\tbinom{d+2}{2}+N-2$. This bound improves, in general, the bound $n\le d(N+1)$ given by G. Hein in \cite{B}, Appendix A. In the last part of the paper, we study moduli spaces of stable rank $n-1$ vector bundles on $\PP^N$ containing syzygy bundles. We prove that if $N+1\le n\le\tbinom{d+2}{2}+N-2$ and $N\ne 3$, then the syzygy bundle $E_{d,n}$ is unobstructed and it belongs to a generically smooth irreducible component of dimension $n\tbinom{d+N}{N}-n^2$, if $N \geq 4$, and $n\tbinom{d+2}{2}+n\tbinom{d-1}{2}-n^2$, if N=2.

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。

↑