The degree and scale of environmental destruction become worse and worse because of more and more expanding social reproduction of human being in a long term. 人类社会再生产规模的不断扩大,长期不合理利用环境资源的累积效应,使环境污染和破坏的范围、程度不断扩大和加深。
In the paper, we prove that threshold graphs and degree maximal graphs are two different statements of a class of graphs 'and determine their structures in term of the off-diagonal left-most matrices. 证明了门槛图与度极大图是一类图的两种不同说法,同时用图的对角限制极左矩阵刻画这一类图的结构。