Abstract: A system for extracting relational tuples from sentences is provided. The system includes a bootstrapper, an open pattern learner, and a pattern matcher. The bootstrapper generates training data by, for each of a plurality of seed tuples, identifying sentences of a corpus that contains the words of the seed tuple. The open pattern learner learns, from the seed tuples and sentence pairs, open patterns that encode ways in which relational tuples may be expressed in a sentence, The pattern matcher matches the open patterns to a dependency parse of a sentence, identifies base nodes of the dependency parse for the arguments and relation for the relational tuple that the open pattern encodes, and expands the arguments and relation of the relational tuple.