Immersion

Immersion --- вложение, погружение.

A pair of adjacent edges [math]\displaystyle{ (u,v) }[/math] and [math]\displaystyle{ (v,w) }[/math], with [math]\displaystyle{ u \neq v \neq w }[/math], is lifted by deleting the edges [math]\displaystyle{ (u,v) }[/math] and [math]\displaystyle{ (v,w) }[/math], and adding the edge [math]\displaystyle{ (u,w) }[/math]. A graph [math]\displaystyle{ H }[/math] is said to be immersed in a graph [math]\displaystyle{ G }[/math] if and only if a graph isomorphic to [math]\displaystyle{ H }[/math] can be obtained from [math]\displaystyle{ G }[/math] by lifting pairs of edges and taking a subgraph.