updates

content/Math4201/Math4201_L35.md

@@ -112,7 +112,7 @@ Recall that $\mathbb{R}_{\ell}$ with lower limit topology is normal. But $\mathb
 
 This shows that $\mathbb{R}_{\ell}$ is not metrizable. Otherwise $\mathbb{R}_{\ell}\times \mathbb{R}_{\ell}$ would be metrizable. Which could implies that $\mathbb{R}_{\ell}$ is normal.
 
-#### Theorem of metrizability
+#### Theorem of metrizability (Urysohn metirzation theorem)
 
 If $X$ is normal and second countable, then $X$ is metrizable.