Interior of Manifold

Definition

Interior Point of Manifold

Consider a Topological Manifold $(M,\mathcal{T})$. The point $x\in M$ is a interior point if a Neighborhood ${\mathcal{N}}_x$ of the point $x$ is homeomorphic to ${\mathbb{R}}^n$. $\exists {\mathcal{N}}_x\text{s.t.}{\mathcal{N}}_x\cong {\mathbb{R}}^n$

Interior of Manifold

$\partial (M)$ The set of interior points of the manifold $M$ is called an interior of $M$.