Shortest-path queries for complex networks: exploiting low tree-width outside the core

  • Authors:

  • Takuya Akiba;Christian Sommer;Ken-ichi Kawarabayashi

  • Affiliations:

  • The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan;MIT CSAIL, Cambridge, MA;National Institute of Informatics, Hitotsubashi, Chiyoda-ku, Tokyo, Japan

  • Venue:
  • Proceedings of the 15th International Conference on Extending Database Technology
  • Year:
  • 2012

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Abstract

We present new and improved methods for efficient shortest-path query processing. Our methods are tailored to work for two specific classes of graphs: graphs with small tree-width and complex networks. Seemingly unrelated at first glance, these two classes of graphs have some commonalities: complex networks are known to have a core--fringe structure with a dense core and a tree-like fringe. Our main contributions are efficient algorithms and data structures on three different levels. First, we provide two new methods for graphs with small but not necessarily constant tree-width. Our methods achieve new tradeoffs between space and query time. Second, we present an improved tree-decomposition-based method for complex networks, utilizing the methods for graphs with small tree-width. Third, we extend our method to handle the highly inter-connected core with existing exact and approximate methods. We evaluate our algorithms both analytically and experimentally. We prove that our algorithms for low-tree-width graphs achieve improved tradeoffs between space and query time. Our experiments on several real-world complex networks further confirm the efficiency of our methods: Both the exact and the hybrid method have faster preprocessing and query times than existing methods. The hybrid method in particular provides an improved tradeoff between space and accuracy.