10. The system of claim 9 , wherein: the sibling query identification component further identify identifies query weightings associated with each of the predicate queries in the group of intersecting predicate queries, each query weighting defining a rate at which an overlapping predicate query preceded a first query or a second query; and produces an adjusted group of overlapping predicate queries comprising those intersecting predicate queries whose weighting exceed a threshold query weighting; and the query map value is based, at least in part, on a quantity of predicate queries that are included in the adjusted group of overlapping queries.
9. A system to identify query suggestions, the system comprising: a data store storing a query log comprising queries received by a search engine; and one or more computers including: a sibling query identification component that identifies a first group of predicate queries, the first group of predicate queries being search queries that were received immediately preceding receipt of a first query; identifies a second group of predicate queries, the second group of predicate queries being search queries that were received immediately preceding receipt of a second query; identifies a group of intersecting predicate queries between the first group of predicate queries and the second group of predicate queries, the group of intersecting predicate queries comprising queries from the first group of predicate queries that have immediately preceded the first query in associated sessions and queries from the second group of predicate queries that have immediately preceded the second query in associated sessions; identifies an intersection set size associated with the group of intersecting predicate queries and a union set size of a union of the first group of predicate queries with the second group of predicate queries; determines a query intersect frequency based on a quotient of the intersection set size over the union set size; derives a query map value associated with the group of intersecting predicate queries, wherein the query map value comprises the query intersect frequency; and identifies the first and second query as sibling queries to one another based upon the query map value exceeding a threshold, and operable to store the sibling queries; and a sibling query suggestion component that receives new search queries; determines whether the new search queries include sibling queries based upon searching a sibling query data store; and provides a suggested query if the new search query includes a sibling query.