“…2 In general, many different mechanisms can be optimal as the distribution of valuations varies, and typically not much is known about the optimal mechanism for a given distribution, except for a few specific settings. For instance, when the valuations are independently and identically distributed, Manelli and Vincent (2006), Pavlov (2011), and Giannakopoulos (2014) solve the problem for uniform or exponential distributions; Hart and Nisan (2014) prove that pure bundling is optimal if the density for each valuation decreases quickly. Hart and Nisan (2014) also try to bound from below the fraction of the optimal profit that can be obtained by selling the objects separately (i.e., posting a suitable price for each object, as in two unrelated one-object settings), or by selling them in a bundle.…”