Não disponível

The main purpose of this work is to describe the primary obstruction of the existence of sections in a (n-1)-oriented fiber bundle whose fiber is (n-2)-conected. We start generalizing the concept of the Euler Class, for (n-1)-oriented fiber bundle and then we prove that this class is the primary obstruction if the fiber is (n-2)-conected. As an application we exhibit result about the topological classification of three dimensional manifolds.