Let G be a graph with adjacency matrix A and diagonal degree matrix D.The eigenvalues of G are the eigenvalues of A.Let εA(λ) ={x ∈ Rn | Ax =λx} be the eige
Graham, Lovász, et al.proved a very attractive theorem about the determinant of the distance matrix D(G) of a strongly connected directed graph G as a function
It is well known that any graph with minimum degree at least k must contain all trees of order k + 1.In this topic, we will discuss some extremal problems and r
A vertex coloring of a graph G is called r-acyclic if it is a proper vertex coloring such that every cycle D receives at least min{|D|,r} colors.The r-acyclic c