The Structure of User-Adviser Dialogues: Is there Method in their Madness?

The Structure of User-Adviser Dialogues: Is there Method in their Madness? Raymonde Guindon Microeleetronies and Computer Technology Corporation - MCC Paul Sladky University of Texas, Austin 8J MCC Hans Brunner Joyee Conner Honeywell - Computer Sciences Center MCC ABSTRACT FOCUSING AND ANAPHORA RESOLUTION Novice users engaged in task-oriented dialogues with an adviser to learn how to use an unfamiliar statistical package. The users', task was analyzed and a task structure was derived. The task structure was used to segment the dialogue into subdialogues associated with the subtasks of the overall task. The representation of the dialogue structure into a hierarchy of subdialogues, partly corresponding to the task structure, was validated by three converging analyses. First, the distribution of non-pronominal noun phrases and the distribution of pronominal noun phrases exhibited a pattern consistent with the derived dialogue structure. Non-pronominal noun phrases occurred more frequently at the beginning of subdialogues than later, as can be expected since one of their functions is to indicate topic shifts. On the other hand, pronominal noun phrases occurred less frequently in the first sentence of the subdialogues than in the following sentences of the subdialogues, as can be expected since they are used to indicate topic continuity. Second, the distributions of the antecedents of pronominal noun phrases and of non-pronominal noun phrases showed a pattern consistent with the derived dialogue structure. FinMly, distinctive clue words and phrases were found reliably at the boundaries of subdialogues with different functions. INTRODUCTION The goal of this paper is to find evidence for the notion of dialogue structure as it has been developed in computational linguistics (Grosz, 1977; Sidner and Grosz, 1985). The role of two hypothesized determinants of discourse structure will be examined: i) the structure of the task that the user is trying to accomplish and the user's goals and plans arising from the task; 2) the strategies available to the user when the user is unable to achieve the task or parts of the task (i.e., meta-plans). The study of dialogue structures is important because computationally complex phenomena such as anaphora resolution have been theoretically linked to the task and dialogue structures. Dialogue Structure: A Key to Computing Focus Given the computational expense of searching, of inferential processing, and of semantic consistency checking required to resolve anaphors, restricting the search a priori to a likely set of antecedents seems advantageous. The a priori restriction on the set of potential antecedents for anaphora resolution has been called focusing (Grosz, 1977; Guindon, 1985; Reichman, 1981; Sidner, 1983). Grosz defines a focus space as that subset of the participant's total knowledge that is in the focus of attention and that is relevant to process a discourse segment. Task-oriented dialogues are dialogues between conversants whose goals are to accomplish some specific tasks by exchanging information through the dialogues. Task-oriented dialogues are believed to exhibit a structure corresponding to the structure of the task being performed. The entire dialogue is segmented into subordinated subdialogues in a manner parallel to the segmentation of …

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