1. A method for detecting inferences from documents, the method comprising: receiving one or more documents; extracting a first set of knowledge relevant to the documents; formulating one or more queries to one or more reference corpora based on the first set of knowledge; extracting a second set of knowledge from results received in response to the queries; and producing a mapping relationship between at least one document and a piece of the second set of knowledge which is not within the first set of knowledge, the mapping relationship indicating an inference from the documents.