15. A computer program product, stored on a non-transitory machine readable storage device, comprising instructions that when executed by data processing apparatus cause the data processing apparatus to perform operations comprising: identifying a first group of predicate queries that have preceded a first query; identifying a second group of predicate queries that have preceded a second query; identifying an intersection set size associated with an intersection set of the first group of predicate queries and the second group of predicate queries, the intersection set defining a set of overlapping predicate queries; identifying a union set size associated with a union set of the first group of predicate queries and the second group of predicate queries; and assigning a quotient of the intersection set size over the union set size as a query intersect frequency for the first query and the second query; deriving a query map value based on the intersect frequency; determining whether the query map value is greater than a threshold query map value; and identifying the first query and second query as suggestions for one another based upon determining that the query map value is greater than the threshold query map value.
15. A computer program product, stored on a non-transitory machine readable storage device, comprising instructions that when executed by data processing apparatus cause the data processing apparatus to perform operations comprising: identifying a first group of predicate queries that have preceded a first query; identifying a second group of predicate queries that have preceded a second query; identifying an intersection set size associated with an intersection set of the first group of predicate queries and the second group of predicate queries, the intersection set defining a set of overlapping predicate queries; identifying a union set size associated with a union set of the first group of predicate queries and the second group of predicate queries; and assigning a quotient of the intersection set size over the union set size as a query intersect frequency for the first query and the second query; deriving a query map value based on the intersect frequency; determining whether the query map value is greater than a threshold query map value; and identifying the first query and second query as suggestions for one another based upon determining that the query map value is greater than the threshold query map value. 16. The computer program product of claim 15 , wherein the query map value comprises a frequency with which one group of predicate queries intersects another group of predicate queries.