He completed his dissertation on categorial grammars at the University of Edinburgh in 2002, advised by Mark Steedman. From 2002 to 2005, he held a post-doctoral position at Edinburgh working with Alex Lascarides and Miles Osborne. His current work includes research on probabilistic parsing for Portuguese, discriminative parse ranking models, probabilistic discourse parsing for Segmented Discourse Representation Theory, active learning, and formal syntax using categorial grammars and other constraint-based formalisms. With Nicholas Asher, he recently began a NSF-funded project to investigate the integration of discourse structure and coreference resolution using machine learning. He has been active for many years in the creation and promotion of open source software for natural language processing.