边数较少时度方和达到次大值的二部图

The bipartite graphs with the second maximum value of the sum of squares of degrees for fewer edges

在给定顶点数和边数且边数较少的情况下,二部图度方和的次大值已经确定.通过讨论顶点数和边数之间的关系,确定了给定顶点数和边数且边数较少时度方和达到次大值所对应的二部图,对度方和问题在二部图中的研究有一定的推动作用.

The second maximum value of the sum of squares of degrees of bipartite graphs with given number of vertices and fewer edges has been determined. The bipartite graphs with given number of vertices and fewer edges where the sum of squares of degrees attain the second maximum value are determined in this paper by discussing the relation of the vertices and edges. It is useful for the research of the sum of squares of degrees for bipartite graphs.