Tame submanifold

Definition

Let $M$ be a manifold of dimension $m$ and $N$ a submanifold of dimension $n$. Then $N$ is termed tame in $M$ if for every point $x\in N$, there exists a neighbourhood $U$ of $x$ in $M$ such that the pair $(U,U\cap N)$ is homeomorphic to the pair $({\mathbb{R}}^m,{\mathbb{R}}^n)$ where ${\mathbb{R}}^n$ is viewed as a linear subspace of ${\mathbb{R}}^m$.

Facts

An example of a submanifold which is not tame is the Alexander horned sphere in ${\mathbb{R}}^3$.