Let $m< n$. Then an $m$-dimensional smooth manifold embedded in $\mathbb R^n$ with boundary is a subset $M \subset\mathbb R^n$ such that for all points $p \in M$, there exists an open set $U \subset H^k$ the closed half-space and an open neighborhood $V \subset M$ of $p$ and a map $\phi: U \to V$ such that
Wikidata ID: Q1333611