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DOI: 10.4230/LIPIcs.APPROX-RANDOM.2017.28
URN: urn:nbn:de:0030-drops-75771
URL: http://drops.dagstuhl.de/opus/volltexte/2017/7577/
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Banks, Jess ; Kleinberg, Robert ; Moore, Cristopher

The Lovász Theta Function for Random Regular Graphs and Community Detection in the Hard Regime

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Abstract

We derive upper and lower bounds on the degree d for which the Lovasz theta function, or equivalently sum-of-squares proofs with degree two, can refute the existence of a k-coloring in random regular graphs G(n,d). We show that this type of refutation fails well above the k-colorability transition, and in particular everywhere below the Kesten-Stigum threshold. This is consistent with the conjecture that refuting k-colorability, or distinguishing G(n,d) from the planted coloring model, is hard in this region. Our results also apply to the disassortative case of the stochastic block model, adding evidence to the conjecture that there is a regime where community detection is computationally hard even though it is information-theoretically possible. Using orthogonal polynomials, we also provide explicit upper bounds on the theta function for regular graphs of a given girth, which may be of independent interest.

BibTeX - Entry

@InProceedings{banks_et_al:LIPIcs:2017:7577,
  author =	{Jess Banks and Robert Kleinberg and Cristopher Moore},
  title =	{{The Lov{\'a}sz Theta Function for Random Regular Graphs and Community Detection in the Hard Regime}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2017)},
  pages =	{28:1--28:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-044-6},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{81},
  editor =	{Klaus Jansen and Jos{\'e} D. P. Rolim and David Williamson and Santosh S. Vempala},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2017/7577},
  URN =		{urn:nbn:de:0030-drops-75771},
  doi =		{10.4230/LIPIcs.APPROX-RANDOM.2017.28},
  annote =	{Keywords: Lov{\'a}sz Theta Function, Random Regular Graphs, Sum of Squares, Orthogonal Polynomials}
}

Keywords: Lovász Theta Function, Random Regular Graphs, Sum of Squares, Orthogonal Polynomials
Seminar: Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2017)
Issue Date: 2017
Date of publication: 31.07.2017


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