A Corpus Study of Negative Imperatives in Natural Language Instructions
  In this paper, we define the notion of a preventative expression and discuss a corpus study of such expressions in instructional text. We discuss our coding schema, which takes into account both form and function features, and present measures of inter-coder reliability for those features. We then discuss the correlations that exist between the function and the form features. 
Keith Vander Linden (University of Brighton), Barbara Di Eugenio   (Carnegie Mellon University)