Lower bounds of Nikiforov's energy over digraphs
2016; Elsevier BV; Volume: 494; Linguagem: Inglês
10.1016/j.laa.2016.01.008
ISSN1873-1856
Autores Tópico(s)Graph Labeling and Dimension Problems
ResumoThe energy of a graph G is defined as E(G)=∑i=1n|λi|, where λ1,λ2,…,λn are the eigenvalues of the adjacency matrix of G. This concept was extended by Nikiforov [8] to digraphs as N(D)=∑i=1nσi, where D is a digraph with n vertices and singular values σ1,…,σn. Upper bounds of N were found by Kharaghani and Tayfeh-Rezaie [4]. In this work we find lower bounds of N over the set of digraphs.
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