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arXiv 1810.03224cs.DScs.DM
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谱子空间稀疏化

Spectral Subspace Sparsification

Huan Li, Aaron Schild

摘要:

我们介绍了一种新的方法,频谱稀疏近似的二次形式的伪逆的图拉普拉斯限制到一个子空间。我们表明,稀疏子空间的维度中的边缘的近线性数量存在。我们的设置概括了舒尔补充稀疏。我们的方法通过对输入图的均匀随机生成树进行采样,并使用该树来指导合同,删除和重新加权边缘的边缘消除过程来产生稀疏器。在舒尔补稀疏的背景下,我们的方法有两个好处比以前的工作。首先,它在几乎线性的时间内产生一个稀疏器,而不依赖于期望的误差。我们直接利用这一点来计算近似的有效电阻的一小组顶点对在更快的时间比以前的工作(Durfee-Kyng-Peeke-Rao-Sachdeva '17)。其次,它产生的稀疏,是重新加权的输入图的未成年人。其结果是,我们给出了一个接近最优的答案的一个变种的施泰纳点去除问题。我们的算法的一个关键组成部分是一个子程序的独立利益:一个近线性时间算法,给定一组选定的顶点,建立一个数据结构,我们可以查询一个乘法近似的两个顶点之间的有效电阻的减少后,确定所有的顶点在选定的集合到一个单一的顶点与逆多项式额外的附加误差在近恒定的时间。

英文摘要:

We introduce a new approach to spectral sparsification that approximates the quadratic form of the pseudoinverse of a graph Laplacian restricted to a subspace. We show that sparsifiers with a near-linear number of edges in the dimension of the subspace exist. Our setting generalizes that of Schur complement sparsifiers. Our approach produces sparsifiers by sampling a uniformly random spanning tree of the input graph and using that tree to guide an edge elimination procedure that contracts, deletes, and reweights edges. In the context of Schur complement sparsifiers, our approach has two benefits over prior work. First, it produces a sparsifier in almost-linear time with no runtime dependence on the desired error. We directly exploit this to compute approximate effective resistances for a small set of vertex pairs in faster time than prior work (Durfee-Kyng-Peebles-Rao-Sachdeva '17). Secondly, it yields sparsifiers that are reweighted minors of the input graph. As a result, we give a near-optimal answer to a variant of the Steiner point removal problem. A key ingredient of our algorithm is a subroutine of independent interest: a near-linear time algorithm that, given a chosen set of vertices, builds a data structure from which we can query a multiplicative approximation to the decrease in the effective resistance between two vertices after identifying all vertices in the chosen set to a single vertex with inverse polynomial additional additive error in near-constant time.

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