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arXiv 2406.03043math.CO
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大部分 $m$-卵形及相关结构的新界与构造

New bounds and constructions for large partial $m$-ovoids and related structures

The University of Western Australia(西澳大学);Delft University of Technology(代尔夫特理工大学)

John Bamberg, Anurag Bishnoi, Ferdinand Ihringer, Ananthakrishnan Ravi

AI总结:

本文利用 $p$-秩界和拉姆齐数界获得有限经典极空间中部分 $m$-卵形的上界,并在二元辛空间中通过无三角形图给出大部分 $m$-卵形的新构造,改进了已有结果。

摘要:

我们利用部分卵形上的 $p$-秩界和拉姆齐数的经典界,在有限经典极空间中获得部分 $m$-卵形大小的上界。这些界在所有有限经典极空间族上导出一个一致的 $m$-卵形不存在性结果。在二元域上的辛空间这一特殊情形中,我们证明了部分 $m$-卵形与极值集理论中被称为 $m$-近正交集的 Oddtown 族推广之间的等价性。我们给出了这些空间中大的部分 $2$-卵形的一个新构造,从而得到二元域上的 $2$-近正交集。该构造使用了与某些 BCH 码相关的无三角形图,这些图的补图具有低 $2$-秩,并且它比之前的最佳构造给出了渐近改进。我们利用二元投影帽给出了无三角形图的另一个构造,该构造在实数域上具有低补秩。这改进了 Beniamini、Linial 和 Shraibman 最近引入的秩-拉姆齐问题中的界。它还在二元辛空间中为 $m > 2$ 的大部分 $m$-卵形提供了更好的构造。

英文摘要:

We use $p$-rank bounds on partial ovoids and the classical bounds on Ramsey numbers to obtain upper bounds on the size of partial $m$-ovoids in finite classical polar spaces. These bounds imply a uniform non-existence result of $m$-ovoids over all families of finite classical polar spaces. In the special case of the symplectic spaces over the binary field, we prove an equivalence between partial $m$-ovoids and a generalisation of Oddtown families from extremal set theory that has been studied under the name of $m$-nearly orthogonal sets. We give a new construction for large partial $2$-ovoids in these spaces and thus $2$-nearly orthogonal sets over the binary field. This construction uses triangle-free graphs associated to certain BCH codes whose complements have low $2$-rank and it gives an asymptotic improvement over the previous best constructions. We give another construction of triangle-free graphs using a binary projective cap, which has low complementary rank over the reals. This improves the bounds in the recently introduced rank-Ramsey problem of Beniamini, Linial, and Shraibman. It also gives better constructions of large partial $m$-ovoids for $m > 2$ in the binary symplectic space.

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。

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