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The Analysis

DICE is a theory which allows us to compute rhetorical links between segments of discourse on the basis of the speaker's background semantic and pragmatic knowledge. Discourse representations produced by DICE are in the form of segmented DRSs (SDRSs) (Asher asher:93a), in which discourses are represented as DRSs plus discourse relations. These discourse relations act as constraints on discourse coherence by constraining the semantic content of the DRSs they connect. For example, if the discourse relation Narration, which conveys that one constituent of the discourse is a consequent of a previous constituent, is to hold, it must be possible to compute a common topic between the two constituents. This explains the incoherence of the discourse in cog4 -- there is no topic shared between the two sentences in the discourse.

  *Max came in. Mary's hair is black.

In this section, I will not give a formal account of the analysis of the discourses in cog3, as the precise details of the formalism are less important than the describiption of how lexical information might interact with discourse-level reasoning. Thus, I will instead give an informal outline of the analysis. The reader is referred to Lascarides and Asher (1991,1993), Lascarides and Copestake (1995), and Lascarides, Copestake and Briscoe lasc_cope_brisc:96 for details of the formal application of DICE.

I label the DRSs representing cog3a,b as tex2html_wrap_inline33676 and the DRSs representing cog3c(i-iii) as tex2html_wrap_inline33678 respectively in Figure 5.7. The DRS tex2html_wrap_inline33680 will represent the indefeasible interpretation He began reading your book at 9pm for cog3c(i), because the sentence has the form begin+NP and so the event read is picked out from the default portion of the telic role in qualia structure through the lexical entry of coercing begin and represented in the logical form as indefeasible. In contrast, tex2html_wrap_inline33682 will represent the interpretation He began doing something with your book at 9pm (there is no default interpretation for what the event done with the book is) and tex2html_wrap_inline33684 represents the defeasible interpretation He particularly enjoyed reading your book. The * marks the fact that the telic event is a default specification. It has remained default after lexicosyntactic processing due to the nature of enjoy+NP. The process by which these interpretations are determined will be described in detail below.

   figure25700
Figure: Logical forms associated with the three discourse continuations in cog3c.

Let us consider how the rules apply to the discourse cog3a,b,c(i). tex2html_wrap_inline33724 must be attached to tex2html_wrap_inline33726 . Assuming that DICE calculates that eating everything in his cage is a subtype of going nuts, we can attach tex2html_wrap_inline33726 to tex2html_wrap_inline33724 with the discourse relation Elaboration, which conveys, as intuitions would dictate, that the event in tex2html_wrap_inline33724 is a part of the event in tex2html_wrap_inline33726 . Now we must incorporate tex2html_wrap_inline33680 into the SDRS tex2html_wrap_inline33738 . We can attempt to attach tex2html_wrap_inline33680 to either tex2html_wrap_inline33726 or tex2html_wrap_inline33724 with a discourse relation.

Attaching tex2html_wrap_inline33680 directly to tex2html_wrap_inline33726 does not seem to be possible. Intuitively, there is no generalisation between tex2html_wrap_inline33726 :going nuts and tex2html_wrap_inline33680 :beginning to read your book, and so there does not seem to be a topic common to the two structures which is consistent with world knowledge about going nuts. Attaching tex2html_wrap_inline33680 to tex2html_wrap_inline33726 with Narration is therefore not possible. Furthermore, the latter event is not a subtype of the former, and so Elaboration is not possible either. Indeed, the rules in DICE will compute that no discourse relation can adequately relate them on the basis of semantic and pragmatic knowledge. Attaching tex2html_wrap_inline33680 to tex2html_wrap_inline33724 also fails in a similar manner. Thus, there is no way to make sense of cog3c(i) given the preceding context and the indefeasible interpretation resulting from lexicosyntactic processing, as cog3a,b,c(i) is predicted in DICE to be an incoherent discourse.

We can contrast this with the discourses cog3a,b,c(ii) and cog3a,b,c(iii). In both discourses, we have the same first step as above: tex2html_wrap_inline33724 is attached to tex2html_wrap_inline33726 with the relation Elaboration. Subsequently, the DRSs for the continuation of the discourses, tex2html_wrap_inline33682 and tex2html_wrap_inline33684 respectively, must be attached. This is done in both cases according to the analysis in L&C (1995) (for details see that paper). Since tex2html_wrap_inline33682 provides only an underspecified interpretation, the context serves to specify tex2html_wrap_inline33772 to tex2html_wrap_inline33774 . This occurs as a result of the constraints imposed by the rhetorical relations; the strongest coherence for the discourse results when tex2html_wrap_inline33682 is in a clear rhetorical relation to the previous discourse. Here, doing something with your book has no clear relation to eating everything in his cage whereas eating your book is a subtype of that event and so the former event is specified to the latter. Similarly, for tex2html_wrap_inline33684 the context overrides the default interpretation tex2html_wrap_inline33780 with tex2html_wrap_inline33774 , via the axiom Discourse Wins combined with the preference for a strongly coherent discourse. In this case, eating your book is in a much stronger rhetorical relation to eating everything in his cage than reading your book is and so the former is preferred. For each of these discourses, then, an interpretation of the continuing sentence is established which would allow DICE to attach the sentence to the discourse via a clear rhetorical relation. This explains the felicity of these discourses in contrast to the discourse cog3a,b,c(i).


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Next: Infeasibility of a purely Up: Logical Metonymy and Pragmatics Previous: Logical Metonymy and Pragmatics