Graph

Definition

Graph

A graph is a pair $G=(V,E)$, where $V$ is a set of vertices and $E$ is a set of edges connecting vertices in $V$.

Directedness

Undirected

Definition

Undirected Graph

A graph $G=(V,E)$ is called undirected if every edge is an unordered pair over the vertices, i.e.,

$$E\subseteq \{\{u,v\}\mid u,v\in V\}.$$

Link to original

Directed

Definition

Directed Graph

A graph $G=(V,E)$ is called directed if every edge is an ordered pair of vertices, i.e.,

$$E\subseteq V\times V.$$

Link to original