Show that the Klein bottle cannot be embedded (as a smooth submanifold)
into \(\mathbb {R}^3\).
It is a fact that the Klein bottle can be embedded into \(\mathbb {R}^4\). Show that no
such embedding \(K\subset \mathbb {R}^4\) can be given by a system of equations \[ f_1=0,\qquad f_2=0 \] with independent
smooth functions \(f_1,f_2\) (i.e. where \(df_1,df_2\) are linearly independent at each point \(x\in K\)).