the Good-Service-or-Money in a Potential-Sale that may becomethe Product-Sold in a possible future Sale.
(<=> (Product ?X)
(Or (Exists (?Sale) (Product-Sold ?Sale ?X))
(Exists (?For-Sale) (Product-For-Sale ?For-Sale ?X))
(Exists (?Potential-Sale)
(Potential-Product ?Potential-Sale ?X))))