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On The Skew Energy of Oriented Unicyclic Digraphs

Zhao Wang1, Teng Ma1, Yaping Mao1, Chengfu Ye1
1Department of Mathematics, Qinghai Normal University, Xining, Qinghai 810008, China

Abstract

The concept of the skew energy of a digraph was introduced by Adiga, Balakrishnan and \(S_0\) in \(2010\). Let \(\overrightarrow{G}\) be an oriented graph of order \(n\) and \(\lambda_1, \lambda_2, \dots, \lambda_n\) denote all the eigenvalues of the skew-adjacency matrix of \(\overrightarrow{G}\). The skew energy \(\varepsilon_s(\overrightarrow{G}) = \sum\limits_{i=1}^{n} |\lambda_i|\). Hou, Shen and Zhang determined the minimal and the second minimal skew energy of the oriented unicyclic graphs. In this paper, the oriented unicyclic graphs with the third, fourth and fifth minimal skew energy are characterized, respectively.

Keywords: unicyclic graphs; oriented graph; skew-adjacency matrix; skew energy