All open problems
Source labels openChecked July 26, 2026
Conjecture about cardinality of Lindelöf spaces
Is there a Lindelöf space with singletons as Gδ sets with cardinality greater than the continuum?
Mathematical statement
Is there a Lindelöf space with singletons as Gδ sets with cardinality greater than the continuum?
Statement source: Papers statement material
Statement terms: Source-specific
Source-specific terms. Therefore does not assert reuse rights beyond attributed display.
Statement artifacts, not proofs
These records expose exact Lean propositions and statement-only wrappers. Defining a proposition does not supply a proof of it. A placeholder-bearing target also contains no proof. Elaboration checks syntax and types; it does not certify that a formalization perfectly captures every nuance of the informal problem.
Pinned Lean formulation 1
HasG
Complete statement target, proof intentionally absentLean 4
theorem HasGδSingletons.lindelof_card : ∃ (X : Type) (_ : TopologicalSpace X), HasGδSingletons X ∧ LindelofSpace X ∧ 𝔠 < #X := by sorry- Statement source
- Formal Conjectures
- Lean version
- v4.27.0
- Placeholder
- Present; no proof artifact
- Source evidence
- Pinned source index
- Fidelity review
- Community formulation
References