1. A method, implemented by a computing system, for deriving facts, comprising: obtaining data identifying a set of seed fact pairs, wherein each seed fact pair associates a fact subject phrase with an information phrase; determining that a first sentence matches a first seed fact pair in the set of seed fact pairs, wherein determining that the first sentence matches the first seed fact pair comprises determining that the fact subject phrase and the information phrase from the first seed fact pair both occur in the first sentence separated by one or more terms; extracting, by the system, from the first sentence, a basic infix-only pattern that includes the one or more terms that separate the fact subject phrase from the information phrase in the first sentence; generating, by the system, a generalized infix-only extraction pattern from the basic infix-only pattern, wherein generating the generalized infix-only extraction pattern from the basic infix-only pattern comprises: determining that a first term of the one or more terms that separate the fact subject phrase from the information phrase in the first sentence belongs to a first distributionally similar class, and substituting the first distributionally similar class for the first term in the basic infix-only pattern; determining that a second sentence matches the generalized infix-only pattern, comprising determining that the second sentence includes a term that belongs to the first distributionally similar class; and applying, by the system, the generalized infix-only pattern to the second sentence to extract a candidate fact pair from the second sentence.