Analyzing and characterizing small-world graphs

  • Authors:
  • Van Nguyen;Chip Martel

  • Affiliations:
  • Computer Science, UC Davis, CA;Computer Science, UC Davis, CA

  • Venue:
  • SODA '05 Proceedings of the sixteenth annual ACM-SIAM symposium on Discrete algorithms
  • Year:
  • 2005

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Abstract

We study variants of Kleinberg's small-world model where we start with a k-dimensional grid and add a random directed edge from each node. The probability u's random edge is to v is proportional to d(u,v)-r where d(u,v) is the lattice distance and r is a parameter of the model.For a k-dimensional grid, we show that these graphs have poly-log expected diameter when k r k, but have polynomial expected diameter when r 2k. This shows an interesting phase-transition between small-world and "large-world" graphs.We also present a general framework to construct classes of small-world graphs with Θ(log n) expected diameter, which includes several existing settings such as Kleinberg's grid-based and tree-based settings [15].We also generalize the idea of 'adding links with probability α the inverse distance' to design small-world graphs. We use semi-metric and metric functions to abstract distance to create a class of random graphs where almost all pairs of nodes are connected by a path of length O (log n), and using only local information we can find paths of poly-log length.