All open problems
Source labels openChecked July 26, 2026
Erdős Problem 723: Eq 12
It is open whether there exists a projective plane of order 12.
Mathematical statement
It is open whether there exists a projective plane of order 12.
Statement source: Erdős Problems 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
erdos_723.variants.eq_12
Complete statement target, proof intentionally absentLean 4
theorem erdos_723.variants.eq_12 : answer(sorry) ↔ ∃ (P L : Type) (_ : Membership P L) (_ : Fintype P) (_ : Fintype L) (pp : ProjectivePlane P L), pp.order = 12 := 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