Graphs with magnetic Schrödinger operators of low corank

  • Authors:
  • Hein van der Holst

  • Affiliations:
  • Freie Universität Berlin, Fachbereich Mathematik und Informatik, Institute für Mathematik, Arnimallee 2-6, D-14195 Berlin, Germany

  • Venue:
  • Journal of Combinatorial Theory Series B
  • Year:
  • 2002

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Abstract

Colin de Verdière (1998, J. Combin. Theory, Ser. B. 74, 121-146) introduced the graph parameter v(G), which is defined as the maximal corank of any positive semidefinite magnetic Schrödinger operator fulfilling a certain transversality condition. He showed that for connected simple graphs, v(G) ≤ 1 if and only if G is a tree. In this paper we characterize for k = 2, 3, the classes of graphs G with v(G) ≤ k.