Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for natural language processing. One of the methods includes receiving a search query from a user during a user session; obtaining a plurality of prior search queries by the user received during the user session; generating a plurality of candidate query rewrites, wherein the candidate query rewrites are derived from the search query and the plurality of prior search queries by the user; scoring each candidate query rewrite, wherein scoring each candidate rewrite includes determining a quality of each candidate query rewrite based on an analysis of search results responsive to the candidate query rewrite; selecting a candidate query rewrite having a score that satisfies a threshold value; and providing search results responsive to the selected candidate query rewrite.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating query suggestions based on search data. In one aspect, a method includes receiving, by one or more computers, a first query, determining query refinements based on the first query, generating, from the query refinements, refinement clusters, each refinement cluster corresponding to a particular topic and each refinement cluster including query refinements that are determined to belong to the particular topic to which the refinement cluster corresponds, ranking the refinement clusters, and selecting the refinement cluster that is highest in the ranking relative to other refinement clusters in the ranking as a first search refinement cluster for the first query.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for receiving a query provided by a user and comprising one or more terms. Obtaining context data based on at least a portion of a first resource displayed to the user at a time that the query is received. Obtaining a revised query that is based on the query and the context data. Receiving a plurality of search results responsive to the revised query. Automatically, selecting a search result that represents a second resource from the plurality of search results, and providing the second resource for display to the user.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for natural language processing. One of the methods includes receiving a search query from a user during a user session; obtaining a plurality of prior search queries by the user received during the user session; generating a plurality of candidate query rewrites, wherein the candidate query rewrites are derived from the search query and the plurality of prior search queries by the user; scoring each candidate query rewrite, wherein scoring each candidate rewrite includes determining a quality of each candidate query rewrite based on an analysis of search results responsive to the candidate query rewrite; selecting a candidate query rewrite having a score that satisfies a threshold value; and providing search results responsive to the selected candidate query rewrite.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for determining query refinements using search data. In one aspect, a method includes receiving a first query and a second query each comprising one or more n-grams for a user session, determining a first set of query refinements for the first query, determining a second set of query refinements from the first set of query refinements, each query refinement in the second set of query refinements including at least one n-gram that is similar to an n-gram from the first query and at least on n-gram that is similar to an n-gram from the second query, scoring each query refinement in the second set of query refinements, selecting a third query from a group consisting of the second set of query refinements and the second query, and providing the third query as input to a search operation.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating query suggestions based on search data. In one aspect, a method includes receiving, by one or more computers, a first query, determining query refinements based on the first query, generating, from the query refinements, refinement clusters, each refinement cluster corresponding to a particular topic and each refinement cluster including query refinements that are determined to belong to the particular topic to which the refinement cluster corresponds, ranking the refinement clusters, and selecting the refinement cluster that is highest in the ranking relative to other refinement clusters in the ranking as a first search refinement cluster for the first query.