Supported by National Natural Science Foundation of China(Grant No.19971086)
Let G be a finite simple graph with adjacency matrix A, and let P(A) be the convex closure of the set of all permutation matrices commuting with A. G is said to be compact if every doubly stochastic matrix which com...
Supported by the National Natural Science Foundation of China (No.19971086);the Doctoral Foundation of Hainan University
Erds and Sós conjectured in 1963 (see [1],Problem 12 in 247) that every graph G on n verticeswith size e(G)>1/2n(k-1) contains every tree T of size k.In this paper,we prove the conjecture for graphswhose complements ...
Supported by National Natural Science Foundation of China(Grant No.19971086)
We first apply non-negative matrix theory to the matrix K=D+A,where D and A are the degree-diagonal and adjacency matrices of a graph G,respectively,to establish a relation on the largest Laplacian eigenvalue λ_1(G)o...