My artwork for select problems in Alan Hatcher's Algebraic Topology text.
Artwork for orientable surface \(M_{2g}\) of genus \(g=1\) (Torus 'doughnut').
Show that there are no retractions \(r:X \rightarrow A\) in the case where \(X = \mathbb{R}^{3}\) with \(A\) any subset homeomorphic to \(S^{1}\).