1. A method comprising: obtaining a plurality of seed facts, wherein each seed fact identifies a subject entity, an attribute possessed by the subject entity, and an object, and wherein the object is an attribute value of the attribute possessed by the subject entity; generating a plurality of patterns from the seed facts, wherein each of the plurality of patterns is a dependency pattern generated from a dependency parse, wherein a dependency parse of a text portion corresponds to a directed graph of vertices and edges, wherein each vertex represents a token in the text portion and each edge represents a syntactic relationship between tokens represented by vertices connected by the edge, wherein each vertex is associated with the token represented by the vertex and a part of speech tag, and wherein a dependency pattern corresponds to a sub-graph of a dependency parse with one or more of the vertices in the sub-graph having a token associated with the vertex replaced by a variable; applying the patterns to documents in a collection of documents to extract a plurality of candidate additional facts from the collection of documents, wherein applying the patterns to documents in the collection of documents comprises: applying the dependency patterns to documents from the collection of documents to identify matching sentences; generating an extraction from each matching sentence; and aggregating the extractions to generate the candidate additional facts; and selecting one or more additional facts from the plurality of candidate additional facts.