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arXiv 1806.04566math.COmath.GTmath.PR
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随机单纯复形的上同调群的消失

Vanishing of cohomology groups of random simplicial complexes

Oliver Cooley, Nicola Del Giudice, Mihyun Kang, Philipp Sprüssel

摘要:

本文研究了由二项随机$(k+1)$ -一致超图通过取下闭包生成的$k$ -维随机单纯复形,其中$k\geq 2$ .对于每个$1\leq j \leq k-1$,我们确定当所有上同调群的系数在$\mathbb{F}_2$从一维到$j$消失,第零个上同调群是同构的$\mathbb{F}_2$。这个属性是不确定性单调的随机复合物的这个模型,但尽管如此,我们表明,它有一个单一的尖锐的阈值。此外,我们证明了一个首中时的结果,这些上同调群的消失,最后的最小障碍的消失。我们还研究了临界窗内$j$ -次上同调群维数的渐近分布。作为推论,我们推导出[Linial and Meshulam,Combinatorica,2006]中引入的随机单纯复形的不同模型的首中时结果,该结果以前仅针对二维[Kahle and Pittel,Random Structures Algorithms,2016]。

英文摘要:

We consider $k$-dimensional random simplicial complexes that are generated from the binomial random $(k+1)$-uniform hypergraph by taking the downward-closure, where $k\geq 2$. For each $1\leq j \leq k-1$, we determine when all cohomology groups with coefficients in $\mathbb{F}_2$ from dimension one up to $j$ vanish and the zero-th cohomology group is isomorphic to $\mathbb{F}_2$. This property is not deterministically monotone for this model of random complexes, but nevertheless we show that it has a single sharp threshold. Moreover we prove a hitting time result, relating the vanishing of these cohomology groups to the disappearance of the last minimal obstruction. We also study the asymptotic distribution of the dimension of the $j$-th cohomology group inside the critical window. As a corollary, we deduce a hitting time result for a different model of random simplicial complexes introduced in [Linial and Meshulam, Combinatorica, 2006], a result which was previously only known for dimension two [Kahle and Pittel, Random Structures Algorithms, 2016].

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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