ThmDex – An index of mathematical definitions, results, and conjectures.
F9604
Formulation 0
Let $E_1, \, \ldots, \, E_N$ each be a D11: Set such that
(i) $\bigcup_{n = 1}^N E_n$ is a D77: Set union for $E_1, \, \ldots, \, E_N$
Then \begin{equation} E_1 \subseteq \bigcup_{n = 1}^N E_n, \quad E_2 \subseteq \bigcup_{n = 1}^N E_n, \quad \ldots, \quad E_N \subseteq \bigcup_{n = 1}^N E_n \end{equation}