2 Related Work Marcu and Echihabi (2003) train a classifier for implicit intra-sentence discourse relations from explicitly-marked examples in the rhetorical structure theory (RST) treebank, where the relations are automatically labeled by their discourse connectives: for example, labeling the relation as CONTRAST if the connective is but.
sporleder and Lascarides (2008) argue that explicitly marked relations are too different from implicit relations to serve as an adequate supervision signal, obtaining negative results in segmented discourse representation theory (sDRT) relations.