### CHAPTER II.

# PLANAR GRAPHS

A **planar graph** is a collection of **nodes** and **edges** in 2D space.

let planarGraph = new PlanarGraph()

The simple application of a 2D position to every node ushers in a new set of rules and ways of orienting oneself to the graph.

Positions are mapped to the Euclidean plane and are described in terms of X and Y. Two adjacent edges create an interior angle between them. It's now possible for nodes and edges to be **near in proximity** to each other. Edges can enclose a space to create a **face**.

It's now possible for edges to cross each other, something traditionally not allowed in mathematics. Two crossing edges should be resolved into four edges with a new node sitting at their intersection.