We characterize the absolutely Calderón elements of the canonical pair \( (l_{1},c_{0}) \) of sequence spaces in terms of the Peetre \( K \)-functional. This result has been known to the first author since rather long ago but the proof appears here. Also, we formulate a few unsolved problems.

中文翻译：

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关于 Banach 对的绝对 Calderón 元素的 $ K $ 泛函 $ (l_{1},c_{0}) $

我们用 Peetre \( K \)泛函来描述序列空间的规范对 \( (l_{1},c_{0}) \)的绝对 Calderón 元素。第一作者很久以前就知道这个结果，但证明在这里。此外，我们还提出了一些未解决的问题。