권오정

An intersection digraph is a digraph where every vertex $v$ is represented by an ordered pair $(S_v,T_v)$ of sets such that there is an edge from $v$ to $w$ if and only if $S_v$ and $T_w$ intersect. An intersection digraph is reflexive if $S_v\cap T_v\ne \mathrm{\varnothing }$ for every vertex $v$. Compared to well-known undirected …