theorem quantityRelaxTime_pos (e : TwoWorldEconomy N) (n : Fin N)
(hr : 0 < sectorRelaxRate e.toNSectorEconomy n) :
0 < quantityRelaxTime e n hr := by
simp only [quantityRelaxTime]
exact div_pos one_pos hrTwo-World Economy: Price vs. Production Timescale Separation