AAAI 1991 Fall Symposium Series Reports

Computational modeling of discourse structure is a fundamental component of theoretical and application-oriented work in natural language processing. A representation of the underlying structure of a discourse enhances the ability of a natural language system to interpret and generate a wide variety of linguistic phenomena. This symposium was designed to bring together researchers in different areas of discourse to identify common issues, goals, and techniques and exchange associated theoretical and practical results. Fifty-seven people representing the fields of cognitive science, communications studies, computer science, linguistics, and psychology attended from Canada, Italy, Japan, the United Kingdom, and the United States. Over 25 percent of those attending were students. The workshop included a lively panel entitled “Discourse Modeling: Where Are We Now and Where Should We Be Going?” chaired by Karen Sparck Jones, with panelists Barbara Grosz, Livia Polanyi, and Bonnie Webber. There were also eight paper sessions and a poster session. Topics of the paper sessions ranged from empirical methodologies for discourse studies to analyses of particular linguistic constructions to computational modeling of cognitive phenomena. The session entitled Empirical Perspectives on Discourse included reports of experiments in online translation (“Interpreted Telephone Dialogues: A Look at Real-World Discourse Complexities,” Sharon Oviatt) and the generation of descriptions of physical scenes (“The Structure of Natural Descriptions,” Donia Scott and Lyn Pemberton). Discussion focused on appropriate methodologies for empirical studies of discourse and how the results of such studies might be applied to building natural language processing systems. A session entitled Conversational Modeling also involved the analysis of recorded interactions and consisted of papers proposing theoretical accounts of the collaborative nature of discourse. The need to model conversational coordination was described in “Conversation Actions,” David Traum and James Allen, and the importance of establishing mutual belief between speaker and hearer served as an explanation for “Redundancy in Collaborative Dialogue” by Marilyn Walker. Several sessions centered on discourse-oriented analyses of particular linguistic phenomena. Tense, aspect, and temporal adverbials were the topic of one of these sessions, with papers entitled “Tense Trees as the ‘Fine Structure’ of Discourse,” by Chung Hee Hwang and Lenhart Schubert, and “Temporal Analysis and Discourse Processing,” by Fei Song. In a session on the discourse functions of syntactic constructions, Judy Delin and Jon Oberlander discussed the interpretation of cleft constructions in “Clefts, Aspectual Class, and the Structure of Discourse,” and Daniel Hardt presented “A Discourse Model Approach to VP Ellipsis.” A session on anaphoric reference in discourse produced the most memorable examples of the workshop and included papers by Rebecca Passonneau entitled “Persistence of Linguistic Form in Discourse Processing” and Gregory Ward, Gail McKoon Roger Ratcliff, and Richard Sproat entitled “How Morphosyntactic and Pragmatic Factors Affect the Accessibility of Discourse Entities.” Intonation and Discourse, a relatively new area in discourse studies, was the title of another session. The session included papers by Beth Ann Hockey on the interpretation of the discourse marker “ok” (“Prosody and the Interpretation of ‘Okay’”) and Richard Oehrle (“Grammatical Structure and Intonational Phrasing”). The types of knowledge that should be included in a discourse model were the focus of one session, with proposals from Lynn Lambert and Sandra Carberry (“A Tripartite, Plan-Recognition Model for Structuring Discourse”), Susann LuperFoy and Elaine Rich (“A Three-Tiered Discourse Representation for MultiAgent Discourses”), and Johanna Moore and Cecile Paris (“Discourse Structure for Explanatory Dialogues”). The importance of AI reasoning and representation techniques to discourse studies was the topic of a session that included papers entitled “Discourse Generation, Temporal Constraints, and Defeasible Reasoning,” by Jon Oberlander and Alex Lascarides and “An Abductive Account of Repair in Conversation,” by Susan McRoy and Graeme Hirst. In “Risk Taking and Recovery in TaskOriented Dialogue,” Jean Carletta proposed a characterization of communicative strategies as a trade-off between communicative effort and miscommunication risk. There were many lively discussions during the workshop and several recurring themes and issues: (1) the importance of using larger and more carefully designed corpora and applying sound methodologies to their analysis, (2) the need to look at