Abstract We show that there exist whole classes of various boundary value problems having the same characteristic determinant, with the respective problems allowed to have differing orders of the differential equations and to be defined both on intervals and on geometric graphs.

中文翻译：

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具有相同特征行列式的各种光谱问题

摘要 我们证明，存在一整类具有相同特征行列式的各种边值问题，每个问题允许具有不同阶的微分方程，并且可以在区间和几何图上定义。