More on the Colorful Monochromatic Connectivity

  • Ran Gu
  • Xueliang Li
  • Zhongmei Qin
  • Yan Zhao


An edge-coloring of a connected graph is a monochromatically-connecting coloring (MC-coloring, for short) if there is a monochromatic path joining any two vertices, which was introduced by Caro and Yuster. Let mc(G) denote the maximum number of colors used in an MC-coloring of a graph G. Note that an MC-coloring does not exist if G is not connected, in which case we simply let \(mc(G)=0\). In this paper, we characterize all connected graphs of size m with \(mc(G)=1, 2, 3, 4\), \(m-1\), \(m-2\) and \(m-3\), respectively. We use G(np) to denote the Erdős-Rényi random graph model, in which each of the \(\left( {\begin{array}{c}n\\ 2\end{array}}\right) \) pairs of vertices appears as an edge with probability p independent from other pairs. For any function f(n) satisfying \(1\le f(n)<\frac{1}{2}n(n-1)\), we show that if \(\ell n \log n\le f(n)<\frac{1}{2}n(n-1)\), where \(\ell \in \mathbb {R}^+\), then \(p=\frac{f(n)+n\log \log n}{n^2}\) is a sharp threshold function for the property \(mc\left( G\left( n,p\right) \right) \ge f(n)\); if \(f(n)=o(n\log n)\), then \(p=\frac{\log n}{n}\) is a sharp threshold function for the property \(mc\left( G\left( n,p\right) \right) \ge f(n)\).


Coloring Monochromatic Connectivity Random graphs 

Mathematics Subject Classification

05C15 05C40 05C80 



This worl was supported by NSFC Nos. 11371205 and 11531011, and PCSIRT. The authors are very grateful to the reviewers for their valuable suggestions and comments, which helped to improve the presentation of the paper.


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Copyright information

© Malaysian Mathematical Sciences Society and Universiti Sains Malaysia 2015

Authors and Affiliations

  1. 1.Center for Combinatorics and LPMC-TJKLCNankai UniversityTianjinChina

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