This paper has an expository nature. We compare the spectral properties (such as boundedness and compactness) of three families of semi-infinite matrices and point out similarities between them. The common feature of these families is that they can be understood as matrices of some linear operations on appropriate Hardy spaces.

中文翻译：

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三个矩阵族

本文具有说明性性质。我们比较了三族半无限矩阵的谱特性（例如有界性和紧性），并指出它们之间的相似之处。这些族的共同特征是它们可以被理解为适当 Hardy 空间上的一些线性运算的矩阵。