Conjecture about cardinality of Lindelöf spaces #
The conjecture asks for a Lindelöf space where all singletons are G_δ sets and which has cardinality > 𝔠.
This is Problem 1 in https://www.math.md/files/basm/y2013-n2-3/y2013-n2-3-(pp37-46).pdf.pdf
Reference:
- Selected Old Open Problems in General Topology by A. V. Arhangel’skii
theorem
CardinalityLindelof.HasGδSingletons.lindelof_card :
∃ (X : Type) (x : TopologicalSpace X), HasGδSingletons X ∧ LindelofSpace X ∧ Cardinal.continuum < Cardinal.mk X
Is there a Lindelöf space with singletons as Gδ sets with cardinality greater than the continuum?