Let \(n\ge 1\) be a positive integer.
- Give an elementary description of the universal cover \(X\to \mathbb {R}\mathrm {P}^n\) of \(\mathbb {R}\mathrm {P}^n\).
- Describe a CW structure on \(\mathbb {R}\mathrm {P}^n\).
- Compute the cohomology ring \(H^*(\mathbb {R}\mathrm {P}^n;\mathbb {Z}/2)\) and the map (from (a)) \(H^*(\mathbb {R}\mathrm {P}^n;\mathbb {Z}/2)\to H^*(X;\mathbb {Z}/2)\).