The rank of a complex unit gain graph in terms of the rank of its underlying graph

Yong Lu, Ligong Wang, Qiannan Zhou

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Let Φ = (G, φ) be a complex unit gain graph (or T-gain graph) and A(Φ) be its adjacency matrix, where G is called the underlying graph of Φ. The rank of Φ , denoted by r(Φ) , is the rank of A(Φ). Denote by θ(G) = | E(G) | - | V(G) | + ω(G) the dimension of cycle spaces of G, where |E(G)|, |V(G)| and ω(G) are the number of edges, the number of vertices and the number of connected components of G, respectively. In this paper, we investigate bounds for r(Φ) in terms of r(G), that is, r(G) - 2 θ(G) ≤ r(Φ) ≤ r(G) + 2 θ(G) , where r(G) is the rank of G. As an application, we also prove that 1-θ(G)≤r(Φ)r(G)≤1+θ(G). All corresponding extremal graphs are characterized.

Original languageEnglish
Pages (from-to)570-588
Number of pages19
JournalJournal of Combinatorial Optimization
Volume38
Issue number2
DOIs
StatePublished - 15 Aug 2019

Keywords

  • 05C35
  • 05C50
  • Dimension of cycle space
  • Rank of graphs
  • T-gain graph

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