[url=https://en.wikipedia.org/wiki/Planar_graph]Planar graph[/url] ([url=https://en.wikipedia.org/wiki/Schlegel_diagram]Schlegel diagram[/url]) of a convex polyhedra lack scale, distance and shape, but the relationship between points is maintained.[br] [b]Euler's formula[/b] states that if a finite, [url=https://en.wikipedia.org/wiki/Connectivity_%28graph_theory%29]connected[/url], [url=https://en.wikipedia.org/wiki/Planar_graph]planar graph[/url] is drawn in the plane without any edge intersections, and [i]v[/i] is the number of vertices, [i]e[/i] is the number of edges and [i]f[/i] is the number of faces (regions bounded by edges, including the outer, infinitely large region), then [i]v - e + f = 2[/i]. Thanks to Schlegel diagram it is clear that Euler's formula is also valid for [url=https://en.wikipedia.org/wiki/Convex_polyhedron]convex polyhedra[/url].

The skeleton of the octahedron (the vertices and edges) form a graph. It is one of 5 Platonic graphs, each a skeleton of its Platonic solid.