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arXiv 1509.02533cs.SIcs.DS
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吸收随机游走中心性:理论与算法

Absorbing random-walk centrality: Theory and algorithms

Charalampos Mavroforakis, Michael Mathioudakis, Aristides Gionis

摘要:

研究了基于吸收随机游动的图中心性的新概念。给定一个图$G=(V,E)$和一组查询节点$Q\subseteq V$,我们的目标是确定$k$最中心的节点在$G$相对于$Q$。具体来说,我们认为中心节点是吸收的随机游走开始于查询节点$Q$。我们的目标是找到一组$k$中心节点,使随机游走的预期长度最小化,直到吸收。所提出的措施,我们称之为$k$吸收随机游走中心,有利于不同的集,因为它是有益的,以放置$k$吸收节点在图的不同部分,以便“拦截”随机游走,从不同的查询节点开始。尽管在文献中已经考虑了类似的问题定义,在信息检索设置的目标是多样化的Web搜索结果,在本文中,我们正式研究的问题,并证明了它的一些属性。我们表明,该问题是NP-难的,而目标函数是单调的和超模,这意味着一个贪心算法提供的解决方案与近似保证。另一方面,贪心算法涉及昂贵的矩阵运算,这使得在大型数据集上使用它是不可行的。为了应对这一挑战,我们开发了更有效的算法,基于谱聚类和个性化的PageRank。

英文摘要:

We study a new notion of graph centrality based on absorbing random walks. Given a graph $G=(V,E)$ and a set of query nodes $Q\subseteq V$, we aim to identify the $k$ most central nodes in $G$ with respect to $Q$. Specifically, we consider central nodes to be absorbing for random walks that start at the query nodes $Q$. The goal is to find the set of $k$ central nodes that minimizes the expected length of a random walk until absorption. The proposed measure, which we call $k$ absorbing random-walk centrality, favors diverse sets, as it is beneficial to place the $k$ absorbing nodes in different parts of the graph so as to "intercept" random walks that start from different query nodes. Although similar problem definitions have been considered in the literature, e.g., in information-retrieval settings where the goal is to diversify web-search results, in this paper we study the problem formally and prove some of its properties. We show that the problem is NP-hard, while the objective function is monotone and supermodular, implying that a greedy algorithm provides solutions with an approximation guarantee. On the other hand, the greedy algorithm involves expensive matrix operations that make it prohibitive to employ on large datasets. To confront this challenge, we develop more efficient algorithms based on spectral clustering and on personalized PageRank.

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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