Fix typo

Signed-off-by: Marcello Seri <[email protected]>

2-tangentbdl.tex

@@ -837,7 +837,7 @@ \section{The tangent bundle}\label{sec:tangentbundle}
 
   \newthought{Step 3: $TM$ is a manifold.}
   With the procedure delineated above, a countable smooth atlas $\{(U_i, \varphi_i)\}$ of $M$ induces a countable atlas $\{(\pi^{-1}(U_i), \widetilde\varphi_i)\}$ of $TM$.
-  First of all, $\{(\pi^{-1}(U_i)\}$ provides a countable covering of $TM$.
+  First of all, $\{\pi^{-1}(U_i)\}$ provides a countable covering of $TM$.
   We need to show that the topology induced by those charts\footnote{Given a family of functions $\cF$ from the same set $X$ into (possibly different) topological spaces, the topology $\cT_{\cF}$ induced by the functions in $\cF$ is the smallest topology such that all the functions are continuous. It is possible to show that such a topology exists and it has as a basis the set $\{V\subset X \,\mid\, \exists n\in\N, f_i\in\cF, U_i \mbox{ open} : \bigcap_{i=1}^n f_i^{-1}(U_i) \}$.} is Hausdorff and second countable.
 
   Let $(p_1, v_1), (p_2, v_2) \in TM$ be different points: either $p_1\neq p_2$, or $p_1 = p_2$ and $v_1 \neq v_2$.