Let \(f:M\to N\) be a submersion between two smooth manifolds (without boundary).
- Show that \(f\) is an open map, i.e., if \(U\subseteq M\) is open, then \(f(U)\subseteq N\) is open.
- Show that if \(M\) is closed (i.e. compact without boundary) and \(N\) is connected, then \(f\) is onto.
- Show that there is no submersion of a closed manifold to \(\mathbb {R}^n\).