theorem recession_depth_proportional_to_K {J : ℕ}
{ρ : ℝ} {T1 T2 Tstar : ℝ} (hTs : 0 < Tstar)
(hT1 : T1 < Tstar) (hT2 : T2 < Tstar) :
effectiveCurvatureKeff J ρ T1 Tstar - effectiveCurvatureKeff J ρ T2 Tstar =
curvatureK J ρ * (T2 - T1) / Tstar := by
simp only [effectiveCurvatureKeff]
have hm1 : 0 < 1 - T1 / Tstar := by rw [sub_pos, div_lt_one hTs]; exact hT1
have hm2 : 0 < 1 - T2 / Tstar := by rw [sub_pos, div_lt_one hTs]; exact hT2
rw [max_eq_right (le_of_lt hm1), max_eq_right (le_of_lt hm2)]
have : Tstar ≠ 0 := ne_of_gt hTs
field_simp
ringMacroeconomic Applications of the CES Potential