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Joined 2026-09-21 Message
Incoming links: Lindelöf space
Lindelöf space 2026-10-31
A Lindelöf space is a topological space in which every open cover has a countable subcover. A closed discrete subset of a Lindelöf space must be countable: cover each of its points by an open set meeting it at only that point and add the open complement. In a metrizable space, the Lindelöf property is equivalent to topological separability.