A Dialogue Manager Using Initiative-Response Units and Distributed Control

A DIALOGUE MANAGER USING INITIATIVE-RESPONSE UNITS AND DISTRIBUTED CONTROL Arne J0nsson Department of Computer and Information Science Linktiping University S- 581 83 LINKOPING, SWEDEN Phone: +46 13281717 Email: ARJ@IDA.LIU.SE Abstract This paper describes a system for managing: dialogue in a natural language interface. The proposed approach uses a dialogue manager as the overall control mecha- nism. The dialogue manager accesses domain independ- ent resources for interpretation, generation and back- ground system access. It also uses information from do- main dependent knowledge sources, which are custom- ized for various applications. Instead of using complex plan-based reasoning, the dialogue manager uses information about possible inter- action structures and information from the specific dia- logue situation to manage the dialogue. This is motivated from the analysis of a series of experiments where users interacted with a simulated natural language interface. The dialogue manager integrates information about segment types and moves into a hierarchical dia- logue tree. The dialogue tree is accessed through a score- board which uses exchangeable access functions. The control is distributed and the dialogue is directed from action plans in the nodes in the dialogue tree. 1 Introduction To achieve true cooperation a natural language inter- face must be able to participate in a coherent dialogue with the user. A common, generally applicable'approach is to use plan-inference as a basis for reasoning:about in- tentions of the user as proposed by, for instance, Allen & Perrault (1980), Litman (1986), Carberry (1989) and Pollack (1986). However, computationally these ap- proaches are not so efficient. Reichman (1985) describes a discourse grammar based on the assumption that a conversation can be de- scribed using conventionalized discourse rules. Gilbert, Buckland, Frolich, Jirotka & Luff (1990) uses interac- tion rules in their menu-based advisory system. Our ap- proach is similar to Reichman and Gilbert el al. In a series of experiments (Dahlb~lck & JOnsson, 1989, J0ns- son & Dahib/tck, 1988) we studied dialogue behaviour in an information-seeking interaction between a human and a computer using a simulated natural language interface (NLI). One important result was that the users followed a rather straightforward information searching strategy which could be well described using conventionalized rules. Reichman uses surface linguistic phenomena for rec- ognizing how the speaker's structure the discourse. We found, however, very little use of surface linguistic cues in our dialogues. In our corpus users normally initiate a request for information, which is followed by an answer from the system. Sometimes the request needs clarifica, tion before the answer can be given as a response to the initial question (this is illustrated in section 4 and 5). Op. tionally the user can interrupt the original question and start a new initiative-response unit, but this also follows the goals of information-seeking. Thus, we adopt a strat, egy in which we employ the notion of adjacency pairs (Schegloff & Sacks, 1973, see also Levinson, 1983: 3030. In our approach the dialogue is planned and utter- ances are interpreted in terms of speech acts. The speech acts are determined on …

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