theorem currency_union_maximizes_Keff (hJ : 2 ≤ J) {ρ : ℝ} (hρ : ρ < 1)
{Tstar : ℝ} (hTs : 0 < Tstar) :
effectiveCurvatureKeff J ρ 0 Tstar = curvatureK J ρ :=
effectiveCurvatureKeff_zero_friction J ρ Tstar hTsOpen Economy Monetary Transmission