US Patent 8001117 Efficient online computation of diverse query results

The system includes a query engine and an advertisement engine. The query engine is configured to receive a query from the user. The advertisement engine generates advertisement results corresponding to the query. The advertisement results are selected from entries in an advertisement database, where the entries include predicate values corresponding to a domain. The advertisement engine generates a diverse advertisement result that is a subset of the database entries that match the query. The diversity result varies at least one predicate by selecting entries for the list that include a proportional representation of each available predicate value in the database that matches the query.