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
Is the given proof of the following correct?
Let $\{A_n\}$ be a sequence of sets, then: $$\liminf_{n\to\infty}=\bigcup_{i=1}^\infty\bigcap_{j=i}^\infty A_j=\{\text{elements that belong to all but finitely many } A_i's\}$$
Pf.
($\leftarrow$) Let $$B_i=\bigcap_{j=i}^\infty A_j$$
Then, $$x\i...