1. A computer-implemented method for extracting structured knowledge from unstructured text for use in a knowledge representation system, the knowledge representation system comprising a knowledge base that represents knowledge using a structured, machine-readable format, the structured, machine-readable format comprising fact triples, each fact triple including two entity objects and a relationship object expressing a relationship between the two entity objects, the method comprising: identifying sentences in the unstructured text using one or more computing devices; using the one or more computing devices, converting each of a subset of the sentences to one or more simplified assertion statements of the form: subject noun phrase, verb phrase, object noun phrase; converting each of a subset of the simplified assertion statements to a corresponding fact triple using the one or more computing devices; and determining a reliability for each of the fact triples using the one or more computing devices.