Definition
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[21J]Let in the following \((J,β€)\) be an ordered set with the filtering property
\begin{equation} β x,yβ J ~ β zβ J,~ x< z\land y< z \end{equation}
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(See section [2FJ]).
A function \(f:JβX\) is called net.
This \(f\) is a generalization of the concept of sequence; indeed the set \(J=β\) with its usual ordering has the filtering property