theorem surplus_loss_is_welfare_loss {ρ H : ℝ} {J : ℕ} : surplusLoss ρ H J = inequalityAversion ρ * (H - 1 / ↑J) := by simp only [surplusLoss, inequalityAversion]
thesis/CESProofs/Applications/SocialWelfare.lean:226
CES as Atkinson Social Welfare Function