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<Paper uid="C96-2101">
  <Title>Goal Formulation based on Communicative Principles</Title>
  <Section position="5" start_page="601" end_page="602" type="evalu">
    <SectionTitle>
4 Discussion and related work
</SectionTitle>
    <Paragraph position="0"> In Section 1 we pointed out three important aspects of dialogues which have been insufficiently accounted for in the earlier approaches to dialogue management. In CDM, these aspects form the basis of the system's functionality: dialogues are regarded as collaborative activities, planned locally in the changed context as reactions to the previous contributions and governed by the rationality principles of Ideal Cooperation. The logical omniscience assumption is tackled by partitioning the Context Model and focussing on specific knowledge with the hel f ) of thematic coherence; also rationality considerations constrain reasoning.</Paragraph>
    <Paragraph position="1"> By adhering to general communicative principles, CDM provides a new and uniform way to treat various phenomena that have been separately studied in previous research: goal formulation, coherence and cooperativeness. Communicative principles fimetion on the following levels: 1. Determination of the joint purpose: reasoning about a communicative strategy in the context (expectations, initiatives, unflflfilled goals, thematic coherence) 2. Selection of the communicative goal: filtering the joint purpose with respect to the agent's role and task.</Paragraph>
    <Paragraph position="2"> 3. Realisation of the goal: specifying the goal in regard to the communicative obligations sincerity, motivation and consideration.</Paragraph>
    <Paragraph position="3"> However, we also use insights from the huge body of research that exists on dialogue management and natural language planning. For instance, the negotiative nature of dialogues is emphasised in (Moore and Paris, 1993) who show how rhetorical knowledge can be combined with the knowledge about the speaker's intentions and communicative goals so that the system can understand follow-up questions or justify its explanations. Our work differs from this in that we study general requirements of communication rather than rhetorical relations and their augmentation with speaker intentions, to determine @propriate responses. It is possible to modify our joint purpose algorithm with information about rhetorical relations so as to check expectations in regard to argmnentation, or to include rhetorical knowledge in the obligations used when reasoning about multisentential contributions, but as our primary goal has been to specify communicative principles and use them in the formalisation of the cooperative and rational nature of dialogues, this kind of extension is left for future.</Paragraph>
    <Paragraph position="4"> (Guinn, 1994) presents a model of mixedinitative negotiation as collaborative problem solving. His Missing Axiom approach demonstrates collaboration and communication between two agents wl~o possess complementary knowledge: if the agent's information is not sufficient to allow  completion of the proof the agent is set to do, the agent attempts to provide the missing axioms through interaction. This is similar to our basic assumption of how domain tasks give rise to eonlinunication. The differences lie again in our einphasis on 'Rational and Cooperative Communication' as opposed to 'Interaction as a FMlure to Prove'.</Paragraph>
    <Paragraph position="5"> In abandoning dialogue grammar and speech act classification, we agree with the common view currently held among researches: dialogue structure is constructed on the basis of the participants' beliefs and intentions, and speech act types are at most convenient abbreviations for a set of attitudes held by the speakers, but do not constitute an explanation of the dialogue (Cohen and Levesque, 1990; Galliers, 1989). We Mso use contextual knowledge extensively, and connect intention-based approaches to practical dialogue management: rationality and cooperation are not only tied to the agent's beliefs and intentions of the desidered next state of the world, but also to the wider social context in which the communication takes place.</Paragraph>
  </Section>
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