Theorem 1.6.1 (Arzela-Ascoli).label Let $K \subset \Omega$, then $K$ is compact if and only if the following holds:

  1. (1)

    $\pi_{0}(K)$ is precompact.

  2. (2)

    For each $N \in \nat$,

    \[\lim_{\delta \to 0}\sup_{\omega \in K}V_{\delta, N}(\omega) = 0\]