18. The system of claim 13 , wherein generalizing one or more of the query patterns comprises replacing a first portion of each of the one or more query patterns that match the particular topic with one or more identifiers.
13. A system comprising: one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: obtaining a collection of query patterns that each include one or more query terms that one or more users of a search engine has indicated are useful in eliciting the search engine to provide an answer that indicates a value for a particular attribute of a particular topic; selecting, from among the collection of query patterns that each include one or more query terms that the one or more users of the search engine has indicated are useful in eliciting the search engine to provide the answer that indicates the value for the particular attribute of the particular topic, a subset of the candidate query patterns of the collection; generalizing one or more of the query patterns of the subset to generate one or more generalized query patterns for eliciting the search engine to provide an answer that indicates a value for the particular attribute of other topics that are different than the particular topic; associating the one or more generalized query patterns with one or more of the other topics that include the particular attribute; receiving a search query that includes the particular attribute and a topic that is (i) different than the particular topic, and (ii) is associated with a particular generalized query pattern from among the one or more generalized query patterns; retrieving a particular value for the particular attribute of the received search query, the particular value being specified by the particular generalized query pattern that includes the topic of the received search query; and generating an answer to the search query that includes the retrieved value for the particular value for the particular attribute of the received search query.