updates

content/Math4202/Math4202_L4.md

@@ -17,6 +17,7 @@ An $m$-dimensional **manifold** is a topological space  $X$ that is
 > Try to find some example that satisfies some of the properties above but not a manifold.
 
 1. Non-Hausdorff
+   - Real line with two origin, as discussed in homework problem
 2. Non-countable basis
    - Consider $\mathbb{R}^\delta$ where the set is $\mathbb{R}$ with discrete topology. The basis must include all singleton sets in $\mathbb{R}$ therefore $\mathbb{R}^\delta$ is not second countable.
 3. Non-local euclidean