### Sidebar

seminars:comb:abstract.200104brin

Louis Kauffman showed that the four-color theorem is equivalent to the existence of solutions of certain equations. These equations involve the cross products of the standard three unit vectors in Euclidean 3-space. We will outline Kauffman's argument and discuss how the equations are parametrized'' by elements of one of Thompson's finitely presented groups. An invitation will then be given to the audience to find a simple proof of the four-color theorem.