Although combinations of tokens could also be replaced by wild cards in any automatically acquired pattern, this would generally lead to an exponentially growing feature space.
the set of discourse markers in our work is fixed: for English, we use 61 markers annotated in the Penn Discourse TreeBank 2.0 (Prasad et al., 2008); for German, we use 155 one-word translations of the English markers, as obtained from an online dictionary.