We investigate signed graphs with just 2 or 3 distinct eigenvalues, mostly in the context of vertex-deleted subgraphs, the join of two signed graphs or association schemes.

中文翻译：

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签名图最多包含三个特征值

我们研究仅具有2或3个不同特征值的签名图，主要是在删除顶点的子图，两个签名图或关联方案的连接的情况下。