In formal terms, a directed graph is an ordered pair G = (V, A) where
• V is a set whose elements are called vertices, nodes, or points;
• A is a set of 展开

An arc (x, y) is considered to be directed from x to y; y is called the head and x is called the tail of the arc; y is said to be a direct successor of x and x is said to be a direct predecessor of y. If a path leads from x to y, then y is said to be a successor of x and … 展开

A directed graph is weakly connected (or just connected ) if the undirected underlying graph obtained by replacing all directed edges of the … 展开

Subclasses
• Symmetric directed graphs are directed graphs where all edges appear twice, one in each direction (that is, … 展开

For a vertex, the number of head ends adjacent to a vertex is called the indegree of the vertex and the number of tail ends adjacent to a vertex is its outdegree (called 展开

The degree sequence of a directed graph is the list of its indegree and outdegree pairs; for the above example we have degree sequence ((2, 0), … 展开

• Binary relation
• Coates graph
• Directed Graph Markup Language
• DRAKON flowchart
• Flow chart 展开