论文标题
光谱算法中两个矩阵的力量用于社区恢复
The Power of Two Matrices in Spectral Algorithms for Community Recovery
论文作者
论文摘要
光谱算法是图形优化和推理问题的一些主要工具。通常,该图被编码为矩阵,然后使用矩阵的特征值和特征值来解决给定的图形问题。光谱算法已成功用于图形分区,隐藏的集团恢复和图形着色。在本文中,我们使用图形分配问题中的两个矩阵研究了光谱算法的功能。我们使用两个不同的矩阵,这些矩阵由同一图的两个不同编码产生,然后结合来自这两个矩阵的光谱信息。 我们分析了两种矩阵光谱算法,以识别大型随机图中潜在社区结构的问题。特别是,我们考虑了在审查的随机块模型中精确恢复社区分配的问题,在审查的随机块模型中,每个边缘状态都以某种概率独立揭示。我们表明,基于两个矩阵的光谱算法是最佳的,并且成功地恢复了社区,直到信息理论阈值。此外,我们表明,对于大多数参数选择,基于一个矩阵的任何光谱算法都是次优的。后一个观察结果与我们先前的作品(2022a,2022b)形成鲜明对比,该作品表明,对于对称随机块模型和种植的密集子图问题,基于一个矩阵的光谱算法可实现信息理论阈值。我们还为光谱算法的(子)出现(子)提供了更一般的几何条件。
Spectral algorithms are some of the main tools in optimization and inference problems on graphs. Typically, the graph is encoded as a matrix and eigenvectors and eigenvalues of the matrix are then used to solve the given graph problem. Spectral algorithms have been successfully used for graph partitioning, hidden clique recovery and graph coloring. In this paper, we study the power of spectral algorithms using two matrices in a graph partitioning problem. We use two different matrices resulting from two different encodings of the same graph and then combine the spectral information coming from these two matrices. We analyze a two-matrix spectral algorithm for the problem of identifying latent community structure in large random graphs. In particular, we consider the problem of recovering community assignments exactly in the censored stochastic block model, where each edge status is revealed independently with some probability. We show that spectral algorithms based on two matrices are optimal and succeed in recovering communities up to the information theoretic threshold. Further, we show that for most choices of the parameters, any spectral algorithm based on one matrix is suboptimal. The latter observation is in contrast to our prior works (2022a, 2022b) which showed that for the symmetric Stochastic Block Model and the Planted Dense Subgraph problem, a spectral algorithm based on one matrix achieves the information theoretic threshold. We additionally provide more general geometric conditions for the (sub)-optimality of spectral algorithms.