Under study are the questions of closedness of an elementary net (carpet) over a field. Every complete net is closed (admissible). We construct an example of a closed elementary net over a field of characteristic 0 which cannot be supplemented to a complete net.

中文翻译：

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特征域0上的封闭基本网

正在研究的是田野上基本网（地毯）的封闭性问题。每个完整的网都是封闭的（允许的）。我们构造了一个特征为0的封闭基本网的示例，该字段不能补充为完整的网。