(<=> (Quantity-Function-Total-On ?Quantity-Function ?Class) (And (Quantity-Function ?Quantity-Function) (Class ?Class) (Total-On ?Quantity-Function ?Class)))
(=> (Quantity-Function-Total-On $X $Y) (Class $Y)) (=> (Quantity-Function-Total-On $X $Y) (Quantity-Function $X)) (<=> (Quantity-Function-Total-On ?Quantity-Function ?Class) (And (Quantity-Function ?Quantity-Function) (Class ?Class) (Total-On ?Quantity-Function ?Class)))