Complexity of product positioning and ball intersection problems

The product positioning problem consists in choosing the attributes of a new product in such a way as to maximize its market share, i.e., to attract a maximum number of customers. Mathematically, the problem can be formulated as follows: given a set of balls (with respect to some norm) and a weight associated to each ball, find a point which maximizes the sum of the weights of the balls containing it. The complexity of this problem is investigated in the case of the L∞ and of the Euclidean norms. In both cases, the problem is proved to be NP-hard, but to be polynomially solvable when the dimension of the space is fixed.