second-countable space

Summary

second-countable space ranks in the top 2% of general entities by monthly Wikipedia readership (107 views/month).^[1]

Key Facts

• second-countable space's subclass of is recorded as separable space^[2].
• second-countable space's subclass of is recorded as first-countable space^[3].
• second-countable space's subclass of is recorded as Lindelöf space^[4].
• second-countable space's Freebase ID is recorded as /m/03n7cy^[5].
• second-countable space's defining formula is recorded as \exists\mathcal B\subset\operatorname{Open}(X)\colon|\mathcal B|\le\aleph_0\land\forall U\in\operatorname{Open}(X)\exists B\in\mathcal B\colon B\subset U^[6].
• second-countable space's BabelNet ID is recorded as 03793325n^[7].
• second-countable space's MathWorld ID is recorded as SecondCountableSpace^[8].
• second-countable space's MathWorld ID is recorded as SecondCountableTopology^[9].
• second-countable space's nLab ID is recorded as second-countable space^[10].
• second-countable space's maintained by WikiProject is recorded as WikiProject Mathematics^[11].
• second-countable space's Microsoft Academic ID is recorded as 162362422^[12].
• second-countable space's ProofWiki ID is recorded as Definition:Second-Countable_Space^[13].
• second-countable space's in defining formula is recorded as X^[14].
• second-countable space's in defining formula is recorded as \mathcal B^[15].
• second-countable space's in defining formula is recorded as \aleph_0^[16].
• second-countable space's in defining formula is recorded as \operatorname{Open}(X)^[17].
• second-countable space's in defining formula is recorded as U^[18].
• second-countable space's in defining formula is recorded as \land^[19].
• second-countable space's Encyclopedia of Mathematics article ID is recorded as Second_axiom_of_countability^[20].
• second-countable space's PlanetMath ID is recorded as SecondCountable^[21].
• second-countable space's OpenAlex ID is recorded as C162362422^[22].
• second-countable space's Metamath statement ID is recorded as df-2ndc^[23].

Why It Matters

second-countable space ranks in the top 2% of general entities by monthly Wikipedia readership (107 views/month).^[1] It has Wikipedia articles in 10 language editions, a strong signal of global cultural recognition.^[24] It is known by 29 alternative names across languages and contexts.^[25]