Sporleder and Lascarides (2005) included other features (e.g., words and their stems, Part-of-Speech [POS] tags, positions, segment lengths) in a boosting-based classifier (i.e., BoosTexter [Schapire and Singer 2000]) to further improve relation classification accuracy.
these studies evaluated classification performance on the instances where rhetorical relations were originally signaled (i.e., the discourse cues were artificially removed), and did not verify how well this approach performs on the instances that are not originally signaled.