# Forest

Besides the fact that a forest is a dense collection of trees covering a relatively large area – at least an area larger than woods – a forest can also be something more abstract.

Namely: a disjoint union of trees.

A disjoint union is a modified union operation that indexes the elements according to which set they originated in; disjoint sets have no element in common. And the term ‘trees’ refers to a widely-used data structure that emulates a hierarchical tree structure with a set of linked nodes.

A Labelled Tree with 6 Vertices and 5 Edges

The various kinds of data structures referred to as trees in computer science are similar to trees in graph theory, except that computer science trees have directed edges. Although they do not meet the definition given here, these graphs are referred to in graph theory as ordered directed trees.

So the forest is a graph in the shape of a map of connected points.

For example: imagine a map with point A at the centre connecting with points B, C, and D. Point B connects to point E, point C connects to points F and G, and point D is a dead end. So the image of the forest is created, and all relations have become clear through the exemplifying graph.