中文摘要：

人们已经知道,最小特征值为-α的强正则图,除了有限多个补图连通的强正则图外,分成两个无限类,其中α是一个不小于2的整数.在Graham和Lovász提出最优图类的存在性问题后,Azarija对这个问题给出了肯定的回答.这里刻画了最小特征值为-3的强正则图,而且确定了其中的最优图类.

英文摘要：

It is known that for a fixed integer a ≥ 2, all but finitely many coconnected ones, the strongly regular graphs with smallest eigenvalue - a fall into two infinite families. Graham and Lovdsz raised the question of whether optimistic graphs exist and it was answered positively by Azarija. Here strongly regular graphs were classified with smallest eigenvalue - 3, and the optimistic ones among them were determined.