All open problems
Source labels openChecked July 26, 2026

WikipediaGeometry

Inscribed square problem

Inscribed rectangle problem* Does every Jordan curve admit inscribed rectangles of any given aspect ratio?

Mathematical statement

Inscribed rectangle problem* Does every Jordan curve admit inscribed rectangles of any given aspect ratio?

Statement source: Wikipedia statement material

Statement terms: CC-BY-SA-4.0

Attributed source material. Reuse must follow the linked attribution and share-alike terms.

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

inscribed_rectangle_problem

Canonical source
Complete statement target, proof intentionally absentLean 4
theorem inscribed_rectangle_problem :    answer(sorry)   (γ : Circle  ²) (hγ : IsEmbedding γ) (r : ) (hr : r > 0),       t₁ t₂ t₃ t₄, IsRectangle (γ t₁) (γ t₂) (γ t₃) (γ t₄) r := 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