Says who? On the treatment of speech attributions in discourse structure

1. Says who?On the treatment of speech attributions in discourse structure Gisela Redeker & Markus Egg University of Groningen

2. Overview • Speech and thought in discourse • Attribution in Carlson & Marcu (2001) • Discourse structures as trees • Problems with Carlson & Marcu’s treatment • Our proposal • Conclusions

3. Reporting speech and thought • Direct speech and thought • He said: “Yes, I’ll come to the party.” • He thought: “Yes, I’ll go to the party.” • Indirect speech and thought • He said he’d come to the party. • He thought he’d go to the party. • Not considered here: Description of speech acts or thought contents • He promised to come to the party. • He pledged attendance. • He meant to go to the party.

4. Attribution of speech and thought • Indicators of attribution include: • Speech verbs (say, tell, state, suggest, point out, ask, promise, advise, etc.) • Specialised expressions like English according to, Dutch volgens, or German zufolge; in informal conversational English also go and be like. • Cognitive predicates (think, believe, know, suppose, hope, fear, estimate, expect, see, etc.) Note: Cognitive predicates are often used in reporting a speaker’s disclosure of thoughts or feelings (he thinks/hopes instead of he said: “I think/hope …”) • Attribution phrases can occur before, in between, or after the reported material.

5. Representing reported discourse in the discourse structure • Reported speech and thought can be used to • introduce the reported propositional contents into the current discourse (with the attribution as a mere acknowledgement of the source) • talk about the fact that someone (the agent in the attribution phrase) has said or thought something (and then e.g. contrasting it to someone else’s opinion) • In Rhetorical Structure Theory (RST) this difference could be represented by assigning nuclear status to the attributed material in case (a) and to the attribution phrase in case (b). • Problem: This is not a clear-cut, decidable distinction and thus cannot be the basis for assigning nuclearity.

6. Attribution in Carlson & Marcu (2001) Carlson and Marcu (2001) define an ATTRIBUTION relation that always assigns nuclear status to the attributed material, with the attribution phrase as the satellite. That is, they model case (a) above. In RST-format, that looks like these two examples: (1) (2)

7. Attribution in Carlson & Marcu (2001) • The ATTRIBUTION relation applies to direct and indirect speech and thought. For indirect reports (like example (1)), the nuclearity assignment thus goes against the syntactic intuition that a complement clause has subordinate status. • The definition includes belief attributions (which in news reports are usually based on speech). Note that the attribution satellite here not only specifies a source, but introduces an opaque context within which the reported material has to be interpreted.

8. Attribution in Carlson & Marcu (2001) • Excluded are cases where the attribution phrase does not specify a source (those phrases are not analysed as separate segments). This is in line with the idea that attribution is essentially acknowledgement of a source, but ignores the opacity of belief contexts. It also introduces yet another semantic criterion in the (otherwise mostly syntactically motivated) segmentation rules. • Serious problems arise when the reported material consists of more than one atomic segment (Wolf & Gibson 2005).

9. Excursus: Discourse structures as trees • We assume that discourse has a hierarchical structure in which clause-like atomic segments combine into larger discourse segments. • We model discourse structure as binary trees (but compare our representations to classic RST which allows multi-satellite structures; see Egg & Redeker (fc) for a discussion). • Right frontier constraint (RFC): Treeness implies that only segments in the right frontier of the discourse (in RST: the last segment or the last nucleus) are available for attachment.

10. Problem 1 for Carlson & Marcu (2001) (3) C1 is inaccessible for C4 because of the RFC and thus attaches to C1-C3, yielding the implausible interpretation that C4 is more closely related to the nucleus C2-C3 than to the satellite C1.

11. Problem 2 for Carlson & Marcu (2001) (4) For sentence-final attribution phrases, the representation cannot distinguish between a continuation of the quote and a continuation like (C4’), which is not part of the quote: (C4’) He greeted and drove off with screeching tyres.

12. Our Proposal • Represent attribution phrases as nuclei and the attributed material as satellites. • Move sentence-medial and sentence-final attribution phrases to the front of the sentence to allow for the integration of additional attributed material. • Use an underspecified representation format to allow for uncertainty and ambiguity about the scope of the attribution.

13. Our Proposal: (i) Nuclearity • By assigning nuclear status to the attribution phrase and introducing the attributed material as its satellite, we solve problem 1, as the attribution phrase now remains at the right frontier and is thus available for attachment. (5)

14. Our Proposal: (ii) Order of Segments • The reversed nuclearity assignment does not solve the problem of attribution phrases that are preceded and followed by attributed material (problem 2). • We could represent the fact that the continuation after the attribution phrase is still part of the quote, but not how the quote parts are related: (6)

15. Our Proposal: (ii) Order of Segments • We propose to move all attribution phrases to the beginning of the sentence they occur in. In this way, both the attribution phrase and the attributed material remain at the right frontier and are thus available for continuation, allowing the quotation segments to be related: • The range of the attributed material can now be specified exactly in terms of the satellite. (7)

16. Our Proposal: (iii) Underspecification Where the range of the attributed material is not explicitly marked, world knowledge or pragmatic inference may be required, which may not be readily available. The text may also be genuinely ambiguous as in (6) . The market makers say (C1) they aren’t comfortable carrying big positions in stocks (C2) because they realize (C3) prices can tumble quickly (C4). (wsj_1142) An underspecified representation as proposed e.g. in Egg & Redeker (to appear) allows a representation that leaves the range of the attribution relation unspecified. (6)

17. Conclusions • Representing attribution phrases as satellites (as proposal by Carlson & Marcu 2001) leads to problems in a representation that assumes treeness of discourse structures. • Our proposal can handle those problems while allowing representation of discourse structures as binary trees.