DiMLex: A lexicon of discourse markers for text generation and understanding

Discourse markers ('cue words') are lexical items that signal the kind of coherence relation holding between adjacent text spans; for example, because, since, and for this reason are different markers for causal relations. Discourse markers are a syntactically quite heterogeneous group of words, many of which are traditionally treated as function words belonging to the realm of grammar rather than to the lexicon. But for a single discourse relation there is often a set of similar markers, allowing for a range of paraphrases for expressing the relation. To capture the similarities and differences between these, and to represent them adequately, we are developing DiMLex, a lexicon of discourse markers. After describing our methodology and the kind of information to be represented in DiMLex, we briefly discuss its potential applications in both text generation and understanding. 1 I n t r o d u c t i o n Assuming that text can be formally described (and represented) by means of discourse relations holding between adjacent portions of text (e.g., [Mann, Thompson 1988]), we use the term discourse marker for those lexical items that (in addition to non-lexieal means such as punctuation, aspectual and focus shifts, etc.) can signal the presence of a relation at the linguistic surface. Typically, a discourse relation is associated with a wide range of such markers; consider, for instance, the following variety of CONCESSIONS, which all express the same underlying propositional content. The words treated here as discourse markers are underlined. We were in SoHo; {nevertheless I nonetheless [ however[ still [ yet}, we found a cheap bar. We were in SoHo, but we found a cheap bar anyway. Despite the fact that we were in SoHo, we found a cheap bar. Notwithstanding the fact that we were in SoHo, we found a cheap bar. Although we were in SoHo, we found a cheap