This specification relates to machine learning.
Internet search engines aim to identify resources (e.g., web pages, images, text documents, multimedia context) that are relevant to a user's needs and to present information about the resources in a manner that is most useful to the user. Internet search engines return a set of search results in response to a user submitted query.
Users can search for the answers to fact queries. Conventional search engines can include a database of facts built by extracting data from resources. Typically, the database provides facts indexed by query. If the query matches an entry in the database, the corresponding fact can be presented to the user. Conventional data extraction techniques can be used to collect the database of facts. However, the conventional extraction techniques typically result in erroneous facts being included in the database of facts.