Rumor spreading and vertex expansion

  • Authors:
  • George Giakkoupis;Thomas Sauerwald

  • Affiliations:
  • University of Calgary, Canada;Max-Planck-Institut für Informatik, Saarbrücken, Germany

  • Venue:
  • Proceedings of the twenty-third annual ACM-SIAM symposium on Discrete Algorithms
  • Year:
  • 2012

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Abstract

We study the relation between the rate at which rumors spread throughout a graph and the vertex expansion of the graph. We consider the standard rumor spreading protocol where every node chooses a random neighbor in each round and the two nodes exchange the rumors they know. For any n-node graph with vertex expansion α, we show that this protocol spreads a rumor from a single node to all other nodes in [EQUATION] rounds with high probability. Further, we construct graphs for which Ω(α−1 log2 n) rounds are needed. Our results complement a long series of works that relate rumor spreading to edge-based notions of expansion, resolving one of the most natural questions on the connection between rumor spreading and expansion.