import OAI.Geometry.RuledCovering.Model namespace OAI noncomputable section namespace RuledApproximation def OrthogonalZeroDiagonalStatement : Prop := ∀ A : Plane →L[ℝ] Plane, LinearMap.trace ℝ Plane A.toLinearMap = 0 → LinearMap.det A.toLinearMap < 0 → ∃ R : Plane ≃ₗᵢ[ℝ] Plane, ∃ b c : ℝ, (∀ z : Plane, R.symm (A (R z)) = vec2 (b * z 1) (c * z 0)) ∧ b * c = -LinearMap.det A.toLinearMap ∧ 0 < b * c ∧ |b| ≤ ‖A‖ ∧ |c| ≤ ‖A‖ end RuledApproximation end end OAI