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    时态图顶点介数中心度计算方法

    Vertex Betweenness Centrality Computation Method over Temporal Graphs

    • 摘要: 在社会网络分析中,介数中心度用于衡量顶点对网络结构的贡献大小,是一种广泛使用的顶点重要度衡量指标. 该指标主要通过计算经过顶点的最短路径数来表明顶点的重要性. 目前研究的介数中心度算法主要聚焦在普通图上,针对时态图的研究工作较少. 普通图介数中心度计算方法主要依据Brandes算法设计,Brandes算法有效的关键理论是最短路径的子路径依然是最短路径,即最优子结构特性. 然而时态图包含时态信息,时态路径类型多样,并且时态最短路径并不满足此特性,因此普通图介数中心度计算理论与方法不再适用于时态图. 鉴于此,定义了严格(时态递增)和非严格(时态非递减)2种时态路径类型,并研究了时态图介数中心度计算理论与方法. 提出了一种高效的基于消息传播的2阶段迭代计算框架. 第1阶段采用自顶向下的广度优先遍历方式计算时态最短路径;第2阶段采用自底向上的方式计算顶点的后继节点和孩子节点对其介数中心度的贡献值,并设计了基于消息传播机制的迭代累积计算方法. 为了提高效率和可扩展性,实现了基于OpenMP(open multiprocessing)框架的多线程并行算法FTBC(fast temporal betweenness centrality). 基于8个真实的时态图数据集实验结果表明,与现有方法相比,提出的介数中心度计算方法具有更优的计算性能.

       

      Abstract: In social network analysis, betweenness centrality is utilized to measure the contribution of a vertex to the network structure and is a widely used vertex importance metric. This metric evaluates the vertex importance mainly by counting the number of shortest paths through the vertices. The current studies for betweenness centrality computation mostly focus on general graphs, few focus on temporal ones. For general graphs, the betweenness centrality calculation methods are mainly designed based on the Brandes’ algorithm. The key theory is that the subpaths of a shortest path is still shortest, i.e., the optimal sub-structure property. However, temporal graphs contain temporal information, and there are various types of temporal paths that do not satisfy the optimal sub-structure property. Therefore, the theory and methods for betweenness centrality calculation on general graphs are no longer suitable for temporal graphs. In view of this, we define two types of temporal paths, i.e., strict (ascending timing order) and non-strict (non-descending timing order), and study the theory and methods for betweenness centrality on temporal graphs. An efficient two-stage iterative computing framework based on message propagation is proposed. The first stage adopts the top-down breadth-first traversal paradigm to calculate temporal shortest paths; the second stage employs the bottom-up method to calculate the contributions of the vertex’s successors and children to its betweenness centrality, and designs a message propagation based iterative accumulation method. In order to improve the efficiency and scalability, a multi-thread parallel FTBC (fast temporal betweenness centrality) algorithm based on OpenMP (open multiprocessing) framework is implemented. Using eight real temporal graphs, it’s showed that our proposed betweenness centrality calculation method has better computational performance than state-of-the-art methods in our experiment.

       

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