All open problems
Source labels openChecked July 26, 2026
Mathoverflow 31809
Does there exist a category that is pretriangulated but not triangulated?
Mathematical statement
Does there exist a category that is pretriangulated but not triangulated?
Statement source: MathOverflow statement material
Statement terms: CC-BY-SA-4.0
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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
mathoverflow_31809
Complete statement target, proof intentionally absentLean 4
theorem mathoverflow_31809 : answer(sorry) ↔ (∀ (C : Type*) [Category C] [Preadditive C] [HasZeroObject C] [HasShift C ℤ] [∀ (n : ℤ), (shiftFunctor C n).Additive] [Pretriangulated C], IsTriangulated C) := 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