A characterization of trees with equal 2-domination and 2-independence numbers

Christoph Brause, Michael A. Henning, Marcin Krzywkowski

A set $S$ of vertices in a graph $G$ is a $2$-dominating set if every vertex of $G$ not in $S$ is adjacent to at least two vertices in $S$, and $S$ is a $2$-independent set if ever…