The unique nature of the open extraction task has led us to develop O-CRF, an open extraction system that uses the power of graphical models to identify relations in text.

Whereas classifiers predict the label of a single variable, graphical models model multiple, in-

Conditional Random Fields (CRFs) (Lafferty et al., 2001), are undirected graphical models trained to maximize the conditional probability of a finite set of labels Y given a set of input observations X.