(<=> (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)))