How do I show this is a topology?[math] \mathscr{T}= \{U \subseteq \mathbb{N} \mid \mathbb{N} - U \hspace{2mm} \textrm{is finite or} \hspace{2mm} 1 \in (\mathbb{N} - U) \}[/math] How do I show it's Hausdorff?
valid question