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arXiv 2512.08652math.AT
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快速构造双过滤链复形的自由解析

Fast free resolutions of bifiltered chain complexes

Technical University of Munich(慕尼黑工业大学);Purdue University(普渡大学);Graz University of Technology(格拉茨理工大学)

Ulrich Bauer, Tamal K. Dey, Michael Kerber, Florian Russold, Matthias Söls

AI总结:

本文提出两种算法,用于将k-临界双过滤转化为1-临界自由链复形,以获得等价同调。第一种算法基于路径图,但存在二次时间复杂度;第二种算法通过保持短路径,实现近线性运行时间。

摘要:

在k-临界双过滤中,每个简单形沿阶梯进入,最多有k步。例子包括度数-Rips双过滤和多覆盖双过滤。本文考虑将k-临界双过滤转化为1-临界(即自由)链复形,以获得等价同调。这被称为计算链复形的自由解析,是处理双过滤的第一步。我们提出两种算法:第一种计算路径图对应的自由解析并组装为链复形,其简单结构在实践中表现良好,但最坏情况复杂度为二次输入规模,因长路径可能导致密集边界矩阵。第二种算法用保持短路径的图替代简单形路径图,从而实现近线性运行时间和输出规模。我们证明预计算自由解析可加速固定维度下双过滤同调的最小表示计算。此外,我们的发现表明,以生成元最少的链复形可能在描述规模上比第二种算法的非最小输出复形更大。

英文摘要:

In a $k$-critical bifiltration, every simplex enters along a staircase with at most $k$ steps. Examples with $k>1$ include degree-Rips bifiltrations and models of the multicover bifiltration. We consider the problem of converting a $k$-critical bifiltration into a $1$-critical (i.e. free) chain complex with equivalent homology. This is known as computing a free resolution of the underlying chain complex and is a first step toward post-processing such bifiltrations. We present two algorithms. The first one computes free resolutions corresponding to path graphs and assembles them to a chain complex by computing additional maps. The simple combinatorial structure of path graphs leads to good performance in practice, as demonstrated by extensive experiments. However, its worst-case bound is quadratic in the input size because long paths might yield dense boundary matrices in the output. Our second algorithm replaces the simplex-wise path graphs with ones that maintain short paths which leads to almost linear runtime and output size. We demonstrate that pre-computing a free resolution speeds up the task of computing a minimal presentation of the homology of a $k$-critical bifiltration in a fixed dimension. Furthermore, our findings show that a chain complex that is minimal in terms of generators can be asymptotically larger than the non-minimal output complex of our second algorithm in terms of description size.

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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