Editing Tree (graph theory) (section)

===Forest===
A {{em|forest}} is an undirected acyclic graph or equivalently a [[disjoint union of graphs|disjoint union]] of trees.  Trivially so, each connected component of a forest is a tree. As special cases, the order-zero graph (a forest consisting of zero trees), a single tree, and an edgeless graph, are examples of forests.
Since for every tree {{math|1=''V'' − ''E'' = 1}}, we can easily count the number of trees that are within a forest by subtracting the difference between total vertices and total edges. {{math|1=''V'' − ''E'' =}} number of trees in a forest.