1. A method comprising, by one or more processors associated with one or more computing devices: receiving search criteria from a first user of an online social network, the search criteria comprising one or more interests; normalizing the one or more interests; selecting one or more second users of the online social network who meet the search criteria, the selecting of each second user being based on: (1) the one or more normalized interests, (2) the interests of the second user, and (3) an estimated probability of compatibility of each pair of interests, each pair including a first interest from the one or more normalized interests and a second interest from the interests of the second user; and sending information associated with the one or more second users.