A digraph is a directed graph; a graph in which the edges have a direction.
This is usually indicated with an arrow on the edge.
A Digraph portrays a Contextual Relation among the elementsof the system and can be converted into an [[Interpretive Structural Model of the system with respect to that relation.
The formal definition is: If v and w are vertices, an edge is an unordered pair {v,w}, while a directed edge, called an arc, is an ordered pair (v,w) or (w,v).