منابع مشابه
On spectral radius of strongly connected digraphs
It is known that the directed cycle of order $n$ uniquely achieves the minimum spectral radius among all strongly connected digraphs of order $nge 3$. In this paper, among others, we determine the digraphs which achieve the second, the third and the fourth minimum spectral radii respectively among strongly connected digraphs of order $nge 4$.
متن کاملOn Quotient Digraphs and Voltage Digraphs
We study the relationship between two key concepts in the theory of digraphs, those of quotient digraphs and voltage digraphs. These techniques contract or expand a given digraph in order to study its characteristics, or obtain more involved structures. As an application, we relate the spectrum of a digraph Γ, called voltage digraph or base, with the spectrum of its lifted digraph Γ. We prove t...
متن کاملNew results on the eccentric digraphs of the digraphs
Let G be a digraph. For two vertices u and v in G, the distance d(u, v) from u to v in G is the length of the shortest directed path from u to v. The eccentricity e(v) of v is the maximum distance of v to any other vertex of G. A vertex u is an eccentric vertex of v if the distance from v to u is equal to the eccentricity of v. The eccentric digraph ED(G) of G is the digraph that has the same v...
متن کاملMore skew-equienergetic digraphs
Two digraphs of same order are said to be skew-equienergetic if their skew energies are equal. One of the open problems proposed by Li and Lian was to construct non-cospectral skew-equienergetic digraphs on n vertices. Recently this problem was solved by Ramane et al. In this paper, we give some new methods to construct new skew-equienergetic digraphs.
متن کاملRemarks on hamiltonian digraphs
An oriented graph is an out-tournament if the out-neighbourhood of every vertex is a tournament. This note is motivated by A. Kemnitz and B. Greger, Congr. Numer. 130 (1998) 127-131. We show that the main result of the paper by Kemnitz and Greger is an easy consequence of the characterization of hamiltonian out-tournaments by Bang-Jensen, Huang and Prisner, J. Combin. Theory Ser. B 59 (1993) 26...
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ژورنال
عنوان ژورنال: Journal of Graph Theory
سال: 2019
ISSN: 0364-9024,1097-0118
DOI: 10.1002/jgt.22535