Notation for the union of all the sets in a family.

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Does anyone know how to write the following: If $\mathcal{F}$ is a family of sets, I want the union of all $X$ in this $\mathcal{F}$.

Thanks in advance!

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3 Answers

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This probably should be migrated to tex.SE.

But:

$$ \bigcup_{X\in \mathcal{F}} X $$ would work.

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Use $\bigcup_{X \in \mathcal F} X$ or simply $\bigcup \mathcal F$.

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Use $\bigcup_i X_i$, if $\mathcal F=\{X_1,X_2,\dots\}$.

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