Compact complement topology

Compact complement topology

In mathematics, the compact complement topology is a topology defined on the set \scriptstyle\mathbb{R} of real numbers, defined by declaring a subset \scriptstyle X \subseteq \mathbb{R} open if and only if it is either empty or its complement \scriptstyle\mathbb{R} \setminus X is compact in the standard Euclidean topology on \scriptstyle\mathbb{R}.

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