Description
(Basic Notions Seminar)

Abstract: 
Although at first the standard definitions of cohomology may seem very strange, I will show how cochain complexes and cohomology arise naturally from the seemingly-trivial study of locally constant functions on smooth manifolds.  As applications, we will see that a manifold cannot retract to its boundary, and that there is no orientation-reversing diffeomorphism of CP^2.
Go to day