第二大特征值不超过(5^(1/2)-1)/2的连通线图

Line Graphs with Second Largest Eigenvalue No More Than (5^(1/2)-1)/2

给出了第二大特征值不超过 5 - 12 的所有连通线图 。

The connected line graphs with the second largest eigenvalue no more than 5-12 are characterized to be three sorts K n, G n and G k(n-k) and ten special graphs A 1～A 10  showed in Figure 1.