Conditional Random Fields: Probabilistic Models for Segmenting and Labeling Sequence Data John Lafferty†∗ LAFFERTY@CS.CMU.EDU Andrew McCallum∗† MCCALLUM@WHIZBANG.COM Fernando Pereira∗‡ FPEREIRA@WHIZBANG.COM ∗ WhizBang! Labs–Research, 4616 Henry Street, Pittsburgh, PA 15213 USA † School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213 USA ‡ Department of Computer and Informati