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Topology

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Moderate

Counting Relatively Compact Subsets

TOPO-NELYVY

Let $X=(\mathbb{Z},\tau)$ be a topological space, where the topology $\tau$ is generated by $\{(n,0,1):n\in\mathbb{Z}, n\not=0,1\}$ and $\{1\}$. Let $Y=\{-1,0,1,2\}\subset X$.