Ramane, H., Nandeesh, K., Gutman, I., Li, X. (2016). Skew equienergetic digraphs. Transactions on Combinatorics, 5(1), 15-23. doi: 10.22108/toc.2016.9372

Harishchandra S. Ramane; K. Channegowda Nandeesh; Ivan Gutman; Xueliang Li. "Skew equienergetic digraphs". Transactions on Combinatorics, 5, 1, 2016, 15-23. doi: 10.22108/toc.2016.9372

Ramane, H., Nandeesh, K., Gutman, I., Li, X. (2016). 'Skew equienergetic digraphs', Transactions on Combinatorics, 5(1), pp. 15-23. doi: 10.22108/toc.2016.9372

Ramane, H., Nandeesh, K., Gutman, I., Li, X. Skew equienergetic digraphs. Transactions on Combinatorics, 2016; 5(1): 15-23. doi: 10.22108/toc.2016.9372

Let $D$ be a digraph with skew-adjacency matrix $S(D)$. The skew energy of $D$ is defined as the sum of the norms of all eigenvalues of $S(D)$. Two digraphs are said to be skew equienergetic if their skew energies are equal. We establish an expression for the characteristic polynomial of the skew adjacency matrix of the join of two digraphs, and for the respective skew energy, and thereby construct non-cospectral, skew equienergetic digraphs on $n$ vertices, for all $n \geq 6$. Thus we arrive at the solution of some open problems proposed in [X. Li, H. Lian, A survey on the skew energy of oriented graphs, arXiv:1304.5707].

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