Simple hypergraph

Simple hypergraph --- простой гиперграф.

A hypergraph [math]\displaystyle{ {\mathcal H} = \{e_{1}, \ldots, e_{m}\} }[/math] is simple, if the condition [math]\displaystyle{ e_{i} \subseteq e_{j} }[/math] implies [math]\displaystyle{ i=j }[/math].