theorem curvatureK_eq_sigma (ρ : ℝ) : curvatureK J ρ = (1 / elasticityOfSubstitution ρ) * (↑J - 1) / ↑J := by simp only [curvatureK, elasticityOfSubstitution] rw [one_div, one_div, inv_inv]
thesis/CESProofs/Applications/Economics.lean:83
Economics extensions for CES formalization: