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Discourse Relations and Defeasible Knowledge

Summary

The paper addresses why short texts with nearly identical syntax get different temporal readings. In "Max stood up. John greeted him" the events follow the order in which they are told. In "Max fell. John pushed him" the second event comes first and causes the first. Since the logical forms are alike, the authors argue that sentence form alone cannot settle the order, and earlier accounts (e.g. Webber 1988, Dahlgren 1988) cannot explain all such cases or lack a proper inference mechanism.

They propose a formal theory in which discourse relations are inferred by default reasoning in MASH, a modal logic for nonmonotonic inference by Asher & Morreau. Two kinds of default rules are encoded:

  • causal world knowledge, such as pushing normally causing falling;
  • Gricean-style pragmatic maxims, such as telling events in the order they happened.

Different readings then follow from standard patterns of default inference, chiefly Penguin-style specificity and the Nixon Diamond. This gives a principled, inference-driven model of how temporal and discourse structure are built from text. The paper is purely theoretical: it uses no corpus or evaluation data.

Key points

  • Discourse relations covered: Narration, Elaboration, Explanation, Background and Result. More than one relation may hold between the same two clauses.
  • Default order rule: Narration applies by default, and an indefeasible axiom says the events then occur in textual order. Specific causal laws, combined with the axiom that causes precede effects, override this through a "Complex" Penguin Principle, which yields Explanation for the falling/pushing example.
  • Background vs. Result: chains of default conflicts (a "Cascaded" Penguin Principle, plus a default that states overlap) yield Background for "The room was pitch dark" after opening a door. The same sentence yields Result after switching off the light. The two relations are shown to be mutually inconsistent.
  • Discourse popping: an unresolvable Nixon Diamond/Polygon conflict blocks attaching a new clause to an embedded one. The clause must then attach higher up, as in the Guy/dancing-competition example.
  • Scope and follow-up: the analysis is limited to texts in the simple past that contain no additional time-related expressions. The approach is reported as extending to the pluperfect (Lascarides & Asher 1991), and temporal connectives and adverbials are left for future work.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

Fields: Linguistics & languages

Topics: Discourse analysis

Cited by

26 papers of our library cite it (of the 140673 whose bibliographies we read); 5 of them have a page here, 21 not yet.

Cite

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.3115/981344.981352

@inproceedings{lascarides1991discourse,
  title = {{Discourse Relations and Defeasible Knowledge}},
  author = {Lascarides, Alex and Asher, Nicholas},
  booktitle = {29th Annual Meeting of the Association for Computational Linguistics},
  year = {1991},
  doi = {10.3115/981344.981352},
  url = {https://doi.org/10.3115/981344.981352}
}

References

22 references, 0 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

  1. Asher, Nicholas [forthcoming] Abstract Objects, Semantics and Anaphora. find
  2. Asher, Nicholas & Morreau, Michael [1991] find
  3. Common Sense Entailment: A Modal Theory of Nonmonotonic Reasoning, in Carlson, Greg & Pelletier, Jeff (eds.) The Generic Book, Proceedings to JELIA90, University of Chicago Press. find
  4. Dahlgren, Kathleen [1988] Naive Semantics for Natural Language Understanding, Kluwer Academic Publishers; Boston, USA. find
  5. Dowty, David [1986] The Effects of Aspeetual Class on the Temporal Structure of Discourse: Semantics or Pragmatics? Linguistics and Philosophy, 9, 37-61. find
  6. Grice, H. Paul [1975] Logic and Conversation. find
  7. In Cole, P. and Morgan, J. L. (eds.) Syntaz and Semantics, Volume 3: Speech Acts, pp41-58. New York: Academic Press. find
  8. Itinrichs, Erhard [1986] Temporal Anaphora in Discourses of English. Linguistics and Philosophy, 9, 63-82. find
  9. Joshi, Aravind, Webber, Bonnie L. & Weischedel, Ralph [1984] Default Reasoning in Interaction. In Proceedings of the Non-Monotonic Reasoning Workshop, AAAI, New York, October, 1984, 144-150. find
  10. Kamp, Hans [1981] A Theory of Truth and Semantic Representation. In Groenendijk, J. A. G., Janssen, T. M. V. and Stokhof, M. B. J. (eds.) find
  11. Formal Methods in the Study of Language, Volume 136, pp277-322. Amsterdam: Mathematical Centre Tracts. find
  12. Kamp, Hans & Rohrer, Christian [1983] Tense in Texts. In Bauerle, R., Schwarze, C. and yon Stechow, A. (eds.) Meaning, Use and Interpretation of Language, pp250-269. Berlin: de Gruyter. find
  13. Lascarides, Alex [1990] Knowledge, Causality and Temporal Representation. Research Report No. HCRC/RP-8, Human Communication Research Centre, University of Edinburgh, Edinburgh, June, 1990. find
  14. Lascarides, Alex & Asher, Nicholas [1991] Discourse Relations and Common Sense Entailment, DYANA deliverable 2.5b, available from Centre for Cognitive Science, University of Edinburgh. find
  15. Lascarides, Alex & Oberlander, Jon [1991] Temporal Coherence and Defeasible Knowledge. In Proceedings to the Workshop on Discourse Coherence, Edinburgh, April 1991. find
  16. Moens, Marc & Steedman, Mark [1988] Temporal Ontology and Temporal Reference. Computational Linguistics, 14, 15-28. find
  17. Partee, Barbara [1984] Nominal and Temporal Anaphora. Linguistics and Philosophy, 7, 243-286. find
  18. Polanyi, Livia [1985] A Theory of Discourse Structure and Discourse Coherence. In Eilfort, W. H., Kroeber, P. D. and Peterson, K. L. (eds.) find
  19. Papers from the General Session at the Twenty-First Regional Meeting of the Chicago Linguistics Society, Chicago, April 25-27, 1985. find
  20. Scha, Remko & Polanyi, Livia [1988] An Augmented Context Free Grammar. In Proceedings of the 121h International Conference on Computational Linguistics and the 24th Annual Meeting of the Association for Computalional Linguistics, Budapest, Hungary, 22-27 August, 1988, 573-577. find
  21. Thompson, Sandra A. & Mann, William C. [1987] Rhetorical Structure Theory: A Framework for the Analysis of Texts. International Pragmaties Association Papers in Pragmatics, 1, 79-105. find
  22. Webber, Bonnie [1988] Tense as Discourse Anaphor. Computational Linguistics, 14, 61-73. find

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