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> Let $\mathbf{G}$ be a group.
>  Let $\{N\_i\}\_{i\in I}$ be a collection of normal subgroups of $\mathbf{G}$, then prove that $\langle \bigcup\_{i\in I} N\_{i}\rangle $ is normal subgroup of $\mathbf{G}$
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We proved this in class, but I didn't understand actually what does $\langle \bigcup\_{i\in I} N\_{i}\rangle$ mean with this notation. Does that mean that this collection of normal subgroups of $\mathbf{G}$ is the generating group of $\mathbf{G}$?