(=> (Market-Need ?Need) (Exists (?Customer) (And (Customer ?Customer) (Has-Need ?Customer ?Need) (Not (Exists (?For-Sale ?Product ?Feature) (And (Product-For-Sale ?For-Sale ?Product) (Has-Feature ?Product ?Feature) (Satisfies-Need ?Feature ?Need)))))))
(<=> (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))))