On the reduction of discourse topic

Asher (2004) argues that developing a formal theory of discourse topic has proved difficult not least because ‘the notion of topic is not a homogeneous one’ [p1]. Against the theoretical background provided by SDRT, Asher helps clarify a number of issues, distinguishing sentence topic, contrastive topic, and discourse topic. He also contrasts ‘themes’, which play a role in the semantics of the relations Parallel and Contrast, the ‘topic’ required by the relation of Alternation, and the discourse topic—henceforth ‘DT’—required by the relations of Narration (Lascarides and Asher 1993, Asher and Lascarides 2003) and Continuation (Asher 1993). DT is the main concern of Asher’s paper; and hence, it is the topic of this paper, also.