A Problem Consider a directed graph stored in adjacency matrix form. Many geometrical objects such as cubes, polyhedra, and wire frame car models, may be thought of as graphs. These graphs are more than just nodes and edges. Their geometrical structure must also be taken into account. For this reason it makes sense to number the edges.
Faces become linked list of edges, and each edge lives in only two faces.
List of Edges Face1 Face2 . . . These are graphs for collection of points in d-dimensional space. Such point sets may be visualized by connecting close points. There are many possible definitions of closeness. For example, one might draw a circle with two data points at diametrically opposite sides.