Restrained dominating set

Restrained dominating set --- ограниченное доминирующее множество.

A set [math]\displaystyle{ D \subseteq V(G) }[/math] is a restrained dominating set of [math]\displaystyle{ G }[/math], if each vertex of [math]\displaystyle{ V(G) - D }[/math] has a neighbour in [math]\displaystyle{ D }[/math], as well as another neighbour in [math]\displaystyle{ V(G) - D }[/math].