theorem dtcPremium_strong_substitute_regime {α σ : ℝ}
(hα : 0 < α) (hα1 : α < 1) (hσ : 2 < σ)
{K₁ K₂ L : ℝ} (hK₁ : 0 < K₁) (hK₂ : 0 < K₂) (hL : 0 < L)
(hK : K₁ < K₂) :
(α / (1 - α)) * (K₁ / L) ^ (σ - 2) <
(α / (1 - α)) * (K₂ / L) ^ (σ - 2) := by
have hα_rat : 0 < α / (1 - α) := div_pos hα (by linarith)
apply mul_lt_mul_of_pos_left _ hα_rat
have hσ2 : 0 < σ - 2 := by linarith
exact rpow_lt_rpow (le_of_lt (div_pos hK₁ hL))
(div_lt_div_of_pos_right hK hL) hσ2Directed Technical Change Extension (Acemoglu 2002)