A video from the American Mathematical
Society's Feature Column "Lorenz and Modular Flows: A
Visual Introduction" by Etienne Ghys and Jos Leys, showing projections of the Riemann sphere.
(Riemann is the person pictured.) See other cool videos by
Ghys and Leys
The figure eight is a 4-regular graph with one vertex and two loops. In Hatcher, there is a
proof that any 4-regular graph evenly covers this graph. In this sequence we visually explore the
connected, simply connected coverings from several vantage points.