Math Professor emeritus at University of California, Berkeley. Currently Honorary Fellow at University of Wisconsin, Madison.
8 Does a connected manifold with vanishing Euler characteristic admit a nowhere-vanishing vector field? Jan 14 '15
5 Ways to prove the fundamental theorem of algebra Aug 8 '12
4 Ways to prove the fundamental theorem of algebra Jul 29 '15
2 Finite groups of planar homeomorphsims Dec 5 '15