- #1

robforsub

- 16

- 0

Let M and N be compact, connected, oriented, smooth manifolds. and suppose F,

G:M->N are diffeomorphisms. If F and G are homotopic, show that they are either

both orientation-preserving or both orientation-reversing.

The hint given in book suggests to use Whitney approximation and Stokes' Theorem

on MxI to prove, however I don't see how should I apply both theorems to solve the prob.