The spectral gap of random graphs with given expected degrees

  • Authors:
  • Amin Coja-Oghlan;André Lanka

  • Affiliations:
  • Institut für Informatik, Humboldt-Universität zu Berlin, Berlin, Germany;Fakultät für Informatik, Technische Universität Chemnitz, Chemnitz, Germany

  • Venue:
  • ICALP'06 Proceedings of the 33rd international conference on Automata, Languages and Programming - Volume Part I
  • Year:
  • 2006

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Abstract

We investigate the Laplacian eigenvalues of a random graph G(n,d) with a given expected degree distribution d. The main result is that w.h.p. G(n,d) has a large subgraph core(G(n,d)) such that the spectral gap of the normalized Laplacian of core(G(n,d)) is $\geq1-c_0{\bar d}_{\min}^{-1/2}$ with high probability; here c00 is a constant, and ${\bar d}_{\min}$ signifies the minimum expected degree. This result is of interest in order to extend known spectral heuristics for random regular graphs to graphs with irregular degree distributions, e.g., power laws. The present paper complements the work of Chung, Lu, and Vu [Internet Mathematics 1, 2003].