The Angles and Main Angles of Some Special Graphs
- 1 Department of Mathematics, Qinghai University for Nationalities, Xining, China
- 2 Department of Mathematics, Qinghai University for Nationalities, Xining, China
Abstract
The eigenvalues of the adjacency matrix of a graph are called the eigenvalues of the graph. Let the vector e j =(0, … , 1, … , 0) T and the all -1 vector j =(1, 1, … ，1) T , the cosine of the (acute) angle formed by the vector e j and the eigensubspace is called an angle of the graph. The cosine of the (acute) angle formed by the vector j and the eigensubspace is called a main angle of the graph. The angles and main angles are all important parameters on the graph, and they can be combined with the eigenvalues of the graph to determine the degree sequence of the graph, the number of triangles, quadrilaterals and pentagons on the graph, and the characteristic polynomials of the complement graph, but there is little study on the angles and main angles of the graph. In this paper, we determine the angles and main angles of the complete graph, the cube graph, the Petersen graph, the cycle and the complete bipartite graph.
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