1. A method of disambiguating a mention of an ambiguous entity, comprising: receiving a document that comprises the mention of the ambiguous entity; retrieving a set of candidate entities from an entity knowledge base based upon the mention of the ambiguous entity, wherein each of the candidate entities has a respective entity feature representation; generating a document feature representation based upon features of the document and the respective entity feature representations of the candidate entities, the document feature representation being generated to comprise features that are part of both: the features of the document; and a union set of features from the entity feature representations of the candidate entities; causing a processor to select a subset of the features from the document feature representation based upon a measure of how discriminative the features from the document feature representation are for disambiguating the mention of the ambiguous entity; and determining a disambiguated result for the mention of the ambiguous entity based upon the subset of the features by employing a posterior probability pursuit algorithm, wherein the disambiguated result is one of: an unknown entity; or one of the candidate entities.