manifolds and cobordisms
cobordism theory, Introduction
Definitions
Genera and invariants
Classification
Theorems
Let be a smooth manifold. By an (embedded) submanifold we mean a smooth immersion of smooth manifolds that is a topological embedding of as a closed subspace of .
In that case, we have that for each , the tangent space is included in the subspace . We define the normal fiber to be the quotient and the normal bundle (with respect to the embedding ) to be the space consisting of pairs , forming a vector bundle over in an evident way. We let denote the zero section. An open neighborhood of the zero section is convex if its intersection with is a convex subset of the vector space .
(Tubular Neighborhood theorem)
For any submanifold , there is an open neighborhood of in and a convex open neighborhood of in and a diffeomorphism such that the diagram
commutes. Such is called a tubular neighbourhood of .
See for instance (Silva 06, theorem 6.5)
Last revised on November 16, 2023 at 09:44:27. See the history of this page for a list of all contributions to it.