|Question||a. Suppose that the antitrust authorities determine that bookselling in physical retail stores and Internet bookselling are individually separate relevant markets. Does any single firm have monopoly power, as defined by the antitrust authorities?
b. Suppose that in fact there is really only a single book industry, in which firms compete both in physical retail stores and via the Internet. According to the antitrust authorities’ measure of monopoly power, is there actually cause for concern?