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<Paper uid="A00-2001">
  <Title>and Discourse Obligations Using Update Rules</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> In this paper we describe a preliminary implementation of a 'middle-level' dialogue management system. The key tasks of a dialogue manager are to update the representation of dialogue on the basis of processed input (generally, but not exclusively, language utterances), and to decide what (if anything) the system should do next. There is a wide range of opinions concerning how these tasks should be performed, and in particular, how the ongoing dialogue state should be represented: e.g., as something very specific to a particular domain, or according to some more general theory of (human or human inspired) dialogue processing. At one extreme, some systems represent only the (typically very rigid) transitions possible in a perceived dialogue for the given task, often using finite states in a transition network to represent the dialogue: examples of this are systems built using Nuance's DialogueBuilder or the CSLU's Rapid Application Prototyper. The other extreme is to build the dialogue processing theory on top of a full model of rational agency (e.g., (Bretier and Sadek, 1996)). The approach we take here lies in between these two extremes: we use rich representations of information states, but simpler, more dialogue-specific deliberation methods, rather than a deductive reasoner working on the basis of an axiomatic theory of rational agency. We show in this paper that the theory of information states we propose can, nevertheless, be used to give a characterisation of dialogue acts such as those proposed by the Discourse Resource Initiative precise enough to formalise the deliberation process of a dialogue manager in a completely declarative fashion.</Paragraph>
    <Paragraph position="1"> Our implementation is based on the approach to dialogue developed in (Traum, 1994; Poesio and Traum, 1997; Poesio and Traum, 1998; Traum et al., 1999). This theory, like other action-based theories of dialogue, views dialogue participation in terms of agents performing dialogue acts, the effects of which are to update the information state of the participants in a dialogue. However, our view of dialogue act effects is closer in some respects to that of (Allwood, 1976; Allwood, 1994) and (Singh, 1998) than to the belief and intention model of (Sadek, 1991; Grosz and Sidner, 1990; Cohen and Levesque, 1990).</Paragraph>
    <Paragraph position="2"> Particular emphasis is placed on the social commitments of the dialogue participants (obligations to act and commitments to propositions) without making explicit claims about the actual beliefs and intentions of the participants. Also, heavy emphasis is placed on how dialogue participants socially GROUND (Clark and Wilkes-Gibbs, 1986) the information expressed in dialogue: the information state assumed in this theory specifies which information is assumed to be already part of the common ground at a given point, and which part has been introduced, but not yet been established.</Paragraph>
    <Paragraph position="3"> The rest of this paper is structured as follows. The theory of dialogue underlying the implementation is described in more detail in Section 2. Section 3 describes the implementation itself. Section 4 shows how the system updates its information state while participating in a fairly simple dialogue.</Paragraph>
  </Section>
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