Chromatic polynomials of random graphs

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Contributors

  • Frank Van Bussel - , Max Planck Institute for Dynamics and Self-Organization, University of Göttingen, Bernstein Center for Computational Neuroscience Göttingen (Author)
  • Christoph Ehrlich - , TUD Dresden University of Technology (Author)
  • Denny Fliegner - , Max Planck Institute for Dynamics and Self-Organization (Author)
  • Sebastian Stolzenberg - , Cornell University (Author)
  • Marc Timme - , Max Planck Institute for Dynamics and Self-Organization, University of Göttingen, Bernstein Center for Computational Neuroscience Göttingen (Author)

Abstract

Chromatic polynomials and related graph invariants are central objects in both graph theory and statistical physics. Computational difficulties, however, have so far restricted studies of such polynomials to graphs that were either very small, very sparse or highly structured. Recent algorithmic advances (Timme et al 2009 New J. Phys. 11 023001) now make it possible to compute chromatic polynomials for moderately sized graphs of arbitrary structure and number of edges. Here we present chromatic polynomials of ensembles of random graphs with up to 30 vertices, over the entire range of edge density. We specifically focus on the locations of the zeros of the polynomial in the complex plane. The results indicate that the chromatic zeros of random graphs have a very consistent layout. In particular, the crossing point, the point at which the chromatic zeros with non-zero imaginary part approach the real axis, scales linearly with the average degree over most of the density range. While the scaling laws obtained are purely empirical, if they continue to hold in general there are significant implications: the crossing points of chromatic zeros in the thermodynamic limit separate systems with zero ground state entropy from systems with positive ground state entropy, the latter an exception to the third law of thermodynamics.

Details

Original languageEnglish
Article number175002
JournalJournal of Physics A: Mathematical and Theoretical
Volume43
Issue number17
Publication statusPublished - 14 Apr 2010
Peer-reviewedYes
Externally publishedYes

External IDs

ORCID /0000-0002-5956-3137/work/142242505