Abstract: The specification relates to a method of receiving a first query and a second query. The method analyzes the second query for a presence of anaphora. If anaphora is present, the method analyzes the first query for a presence of an entity that can be associated with the anaphora. If the analysis analyzing the first query returns two or more associated entities, the method forms a third query wherein the anaphora of the second query is replaced with one of the associated entities and forms a fourth query wherein the anaphora is replaced with the other of the associated entities. The third query and the fourth query are sent to a query-ranking engine. The third query and the fourth query receive a ranking and the higher-ranked query is sent to a search engine.

Abstract: The specification relates to a method of receiving a first query and a second query. The method analyzes the second query for a presence of anaphora. If anaphora is present, the method analyzes the first query for a presence of an entity that can be associated with the anaphora. If the analysis analyzing the first query returns two or more associated entities, the method forms a third query wherein the anaphora of the second query is replaced with one of the associated entities and forms a fourth query wherein the anaphora is replaced with the other of the associated entities. The third query and the fourth query are sent to a query-ranking engine. The third query and the fourth query receive a ranking and the higher-ranked query is sent to a search engine.

Abstract: The specification relates to a method of receiving a first query and a second query. The method analyzes the second query for a presence of anaphora. If anaphora is present, the method analyzes the first query for a presence of an entity that can be associated with the anaphora. If the analysis analyzing the first query returns two or more associated entities, the method forms a third query wherein the anaphora of the second query is replaced with one of the associated entities and forms a fourth query wherein the anaphora is replaced with the other of the associated entities. The third query and the fourth query are sent to a query-ranking engine. The third query and the fourth query receive a ranking and the higher-ranked query is sent to a search engine.

Abstract: In general, the subject matter described in this specification can be embodied in a method that includes: obtaining user feedback associated with quality of an electronic document; adjusting a measure of relevance for the electronic document based on a temporal element of the user feedback; and outputting the measure of relevance to a ranking engine for ranking of search results, including the electronic document, for a search for which the electronic document is returned. Obtaining the user feedback can include receiving user selections of documents presented by a document search service, the method can include evaluating the user selections in accordance with an implicit user feedback model to determine the measure of relevance, and adjusting the measure of relevance can include adjusting the measure of relevance in accordance with the implicit user feedback model.