Directed graph

Definition

A directed graph is a graph, where every edge has a direction. More precisely, a directed graph is a pair [math]\displaystyle{ G=(V,A) }[/math], where [math]\displaystyle{ V }[/math] represents a set of nodes and [math]\displaystyle{ A }[/math] a set of arcs. Arcs are ordered pairs of nodes in contrast to unordered pairs of nodes (called edges) in an undirected graph. An arc [math]\displaystyle{ a = (v, w) }[/math] is considered to be directed from [math]\displaystyle{ v }[/math] to [math]\displaystyle{ w }[/math].