# Graph Theory/Trees

A tree is a type of connected graph. An directed graph is a tree if it is connected, has no cycles and all vertices have at most one parent. An undirected graph is considered a tree if it is connected, has ${\displaystyle |V|-1}$ edges and is acyclic (a graph that satisfies any two of these properties satisfies all three).
${\displaystyle tree}$
Acyclic and connected ${\displaystyle graph}$.
${\displaystyle forest}$ is acyclic graph. So, ${\displaystyle tree\subseteq forest}$