Before revision:  We consider a robust versionof this revenue-maximization pricing problem, where the seller knows the buyer's marginal distributions of values for each item  , but not the joint distribution, and wishes to maximize worst-case revenue over all possible correlation structures.
After revision:  In this robust version, the seller knows the buyer's marginal distributions of values for each item , but not the joint distribution, and wishes to maximize worst-case revenue over all possible correlation structures.