(i) | $\mathcal{P}(X)$ is the D80: Power set of $X$ |
(1) | \begin{equation} \emptyset, X \in \mathcal{T} \end{equation} |
(2) | \begin{equation} \forall \, \mathcal{S} \subseteq \mathcal{T} : \cup \mathcal{S} \in \mathcal{T} \end{equation} |
(3) | \begin{equation} \forall \, N \in 1, 2, 3, \ldots : \forall \, E_1, \dots, E_N \in \mathcal{T} : \bigcap_{n = 1}^N E_n \in \mathcal{T} \end{equation} |