ThmDex – An index of mathematical definitions, results, and conjectures.
Result R4142 on D77: Set union
Union is an upper bound to each set in the union
Formulation 0
Let $E_j$ be a D11: Set for each $j \in J$ such that
(i) $\bigcup_{j \in J} E_j$ is a D77: Set union for $\{ E_j \}_{j \in J}$
Then \begin{equation} \forall \, i \in J : E_i \subseteq \bigcup_{j \in J} E_j \end{equation}
Formulation 1
Let $E_j$ be a D11: Set for each $j \in J$ such that
(i) $\cup E$ is a D77: Set union for $E = \{ E_j \}_{j \in J}$
Then \begin{equation} \forall \, j \in J : E_j \subseteq \cup E \end{equation}