UGroningen: Negation detection with Discourse Representation Structures

We use the NLP toolchain that is used to construct the Groningen Meaning Bank to address the task of detecting negation cue and scope, as defined in the shared task “Resolving the Scope and Focus of Negation”. This toolchain applies the C&C tools for parsing, using the formalism of Combinatory Categorial Grammar, and applies Boxer to produce semantic representations in the form of Discourse Representation Structures (DRSs). For negation cue detection, the DRSs are converted to flat, non-recursive structures, called Discourse Representation Graphs (DRGs). DRGs simplify cue detection by means of edge labels representing relations. Scope detection is done by gathering the tokens that occur within the scope of a negated DRS. The result is a system that is fairly reliable for cue detection and scope detection. Furthermore, it provides a fairly robust algorithm for detecting the negated event or property within the scope.