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<Paper uid="C96-2101">
  <Title>Goal Formulation based on Communicative Principles</Title>
  <Section position="3" start_page="598" end_page="599" type="metho">
    <SectionTitle>
2 Constructive Dialogue Model
</SectionTitle>
    <Paragraph position="0"> 2.1 Rational, (:()operative way to react Rational agents try to follow the principles of Ideal Cooperation (Allwood, 1976) in comimmication: (1) assume a joint l)urpose, (2) show cognitive consideration (epistemic rationality regarding appropriate ways to react) and ethical consideration (intention to react in a way that does not prevent the partner fi'om fiflfilling her goals), and (3) trust, that the partner is acting according to the same principles. Ideal cooperation does not mean that the agents always react in the way the partner intended to evoke, but rather, it sets the normality assumptions for the way the agents would behave if no disturbing factors were present. As (Galliers, 1989) points out, conflict resolution forms an important part of human conmmnication, and if systems are always ready to adopt the user's role, they becolne rigid and unrealistic. However, if the conflict becomes so serious that it makes any cooperation impossible, communication will break down as well. Rational agents thus try to conlnlunicate so as to conforln to the shared assumptions about operationally appropriate and ethically acceptable acts in a given situation (Jokinen, 11995).</Paragraph>
    <Paragraph position="1"> Empirical dialogue research has emphasised collaborative nature of dialogues (Sacks et al., 1974; Clark and Wilkes-Gibbs, 1990). Also computationally oriented dialogue studies show that the users express themselves vaguely and continue with follow-up questions (Moore and Paris, 1993), and our corpus 1 supports the view that even sin&gt; ple information seeking dialogues resemble negotiations rather than straightforward question-answer sequences. Based on these obeservations and the theoretical assumptions of Ideal Cooperation, we distinguished the main factors in rational, co-operative dialogue management as follows: Surface form Expressive intentions Declarative express a belief: want (Sp ,know(He ,P) ) Interrogative desire for information: want (Sp,know(Sp, P) ) hnperative desire for action: want (Sp,do(ge,P)) Exclamative express action: want (Sp, do (Sp,P)) whereas the information seeker is not expected to teach the information provider how to look for the information. The roles can be further difl'erentiated with respect to social factors such as acquaintance of the addressee and fornlality of the situation.</Paragraph>
    <Paragraph position="2"> * Communicative obligations. Social, normative requirements that concern the agent's sincerit'9 (exchange information which is true or for which evidence can be provided), motivation (exchange information which is related to one's goals and strategies), and consideration (exchange information which the.</Paragraph>
    <Paragraph position="3"> partner is able to deal with).</Paragraph>
    <Paragraph position="4"> * Task. Gives rise to communication. Task goals are planned to complete a real workt task (rent a car, book ~ flight, repair a pump) but because of uneven distribution of knowledge, the agents usually need to collaborate to achieve the goal, and thus formulate com,nunicative goals to obtain missing information, el. (Guilm, 1994).</Paragraph>
    <Paragraph position="5"> B. Commmficative act: * Expressive and evocative attitudes. To distinguish between the effects of an utterance and the intentions behind it, Austin's concept of illocution is split up into two: ezpvession of the speaker's attitude and evocation of a reaction in the partner; perlocution corresponds to what is actually achieved by the act: the evoked respoT~se, cf. (Allwood, 1976). Expression may differ fl'om evocation (irony, indirectness), aud the evoked response fi'om the evocative intentions (the agent requests ilfformation that the partner cannot or does not want to disclose; the agent fa.ils to fi'ighten the partner becmme this has guessed the agent's malicious intentions).</Paragraph>
    <Paragraph position="6"> Evocative intentions share the belief: want (Sp, want (He, know(He, P) ) ) provide the desired information:  want (Sp, want (He, know (Sp, P) ) ) (provide) action: want (Sp, want (He, do (He, P) ) ) attend to the action: want (Sp, want (He, do (Sp, P) ) ) Figure 1: Conventional association of expressive and evocative intentions with surface form, modified fi'om (Allwood, 1992). A. Communicative situation: C. Communicative context: * Role. Characterised by global communica- * Expectations. Evocative intentions put  live rights and obligations of the agents. E.g. the information provider is expected to give information which is relevant for the task,  technique with users trying to find information on car\[tire companies and restaurants in a particular area, and is reported in (Nivre, 1992).</Paragraph>
    <Paragraph position="7"> pressure on the agent to react in a particular way. Conventional expectations, carried by the surface form (Fig. 1), serve as anchoring points in reasoning about the partner's communicative goal (Cohen and Levesque, 1990).</Paragraph>
    <Paragraph position="8"> Initiatives. If the agent has initiated a con&gt; municative goal, she &amp;quot;has the initiative&amp;quot; and  also the right to pursue the goal until it is achieved or not relevant anymore. She also has the right to expect the partner to collaborate or at least not prevent the agent from achieving her goal.</Paragraph>
    <Paragraph position="9"> * Unfulfilled goals. If the expressive attitudes of the partner's response match the evocative intentions of the agent's contribution, the communicative goal of the agent's contribution is fulfilled. An unfulfilled goal is pushed forward or stored for later processing.</Paragraph>
    <Paragraph position="10"> When the agent has the right to take the initiative, a previously unfulfilled goal can be taken up. If the goal is still unfulfilled and relevant, it is resumed, otherwise dropped.</Paragraph>
    <Paragraph position="11"> * Thematic coherence. A competent agent relates the topic of her contribution to what has been discussed previously or marks an awkward topic shift appropriately; otherwise the agent risks being understood. Thematic relatedness is based on the types of relationships which occur in the domain.</Paragraph>
    <Section position="1" start_page="599" end_page="599" type="sub_section">
      <SectionTitle>
2.2 The CDM System
</SectionTitle>
      <Paragraph position="0"> The theoretical framework is formalised as an approach to dialogue management called the Constructive Dialogue Model, CDM (Jokinen, 1994).</Paragraph>
      <Paragraph position="1"> In CDM, the dialogue is an instrument to exchange new information on a particular topic to complete a real world task, and it is managed locally by reacting to the changed dialogue context.</Paragraph>
      <Paragraph position="2"> The task division and information flow in a CDM system 2 is shown in Fig. 2. The dialogue manager operates on the Context Model which is a dynamic knowledge base containing facts about the agents' goals, expressive and evocative attitudes, central concepts (topic), and new information. It also has access to three static knowledge bases: Communicative Principles (knowledge about rational, cooperative communication), Application Model (knowledge about tasks and roles), and World Model (general knowledge about the entities and their relations in the world). 3 Dialogue contributions are constructed in three phases corresponding to the three main processing tasl~s. Analysis of the input message results in the user's communicative goal, and contains four subtasks: determine the explicitness level, interpret the propositional content, check coherence and verify obligations. Evaluation of the user goal concerns an appropriate joint purpose and determines the next system goal. Response specifies the system's communicative goal up to the semantic representation using the same subtasks as analysis but in a reverse order. Evaluation and response form the agent's reaction.</Paragraph>
      <Paragraph position="3">  The Context Model is represented as a partitioned Prolog database and the predicates have an extra argument referring to the contribution whose processing introduced them. In the attitude language the predicates know, want and do represent belief, intention and action, respectively, s refers to the system and u to the user. Communicative Principles are reasoning rules of the fort0: if cntxtFactl .... , cntxtFactN then cntxtFactM+1,...,cntxtYactK.</Paragraph>
      <Paragraph position="4"> The World Model uses neo-Davidsonian event representation, and the Application Model provides mappings from World Model concepts to task and role related facts.</Paragraph>
    </Section>
  </Section>
  <Section position="4" start_page="599" end_page="601" type="metho">
    <SectionTitle>
3 Cooperative Goal Formulation
</SectionTitle>
    <Paragraph position="0"> In CDM, joint purpose represents the communicative strategy that an agent has chosen in a particular situation to collaborate with her partner. It is determined by evaluating the partner's goal with respect to the communicative context: expectations, initiatives, unfulfilled goals and coherence.  1. The agent has fulfilled goals only, and the initiative: Finish the dialogue or start a new one depending on the pending task goals (finish/start/continue/obj ect/spe elf y).</Paragraph>
    <Paragraph position="1"> Maintain the initiative if the response is related, give the initiative if unrelated.</Paragraph>
    <Paragraph position="2"> 2. The agent has fulfilled goals only, but no initiative: Adopt the partner's goal.</Paragraph>
    <Paragraph position="3"> Maintain the initiative if the response is expected (follow-up-new,new-request), take the initiative if the response is non-expected (somethingelse ,new- indir-request).</Paragraph>
    <Paragraph position="4"> 3. The agent has unfnlfilled goals, and the initiative: Adopt the partner's goal if  the response is thematically related (backto, subquestion), persist with the own goal if unrelated (repeat-new,object). Maintain the initiative if the response is expected, give the initiative if non-expected.</Paragraph>
    <Paragraph position="5"> 4. The agent has unfulfilled goals, but no initiative: Adopt the partner's goal. Maintain the initiative if the response is thematically related (follow-up-old,continue), take the initiative if unrelated (newquestion, uotrelated).</Paragraph>
    <Paragraph position="6"> The joint purpose describes coinnmnieative intentions in a context where no speaker obligations or considerations hold. In order to attend the requirements of a particular communicative situation, the joint purpose needs to be specified with respect to the agent's role, task and communicative obligations.</Paragraph>
    <Paragraph position="7"> Specification of the joint purpose via the Application Model captures the cognitive consider= ation of Ideal Cooperation: the agent plans her response to be operationally appropriate in the current situation. The result is a communicative goal (c-goal), a set of communicative intentions instantiated according to the current task and role. The c-goal is then filtered through communicative obligations which impleinent the ethical consideration of Ideal Cooperation: the agent's communicative competence shows in the ways she can realise the same c-goal in various situations. Some communicative obligations are listed in Fig. 4.</Paragraph>
    <Paragraph position="8"> Sincerity: &amp;quot;do I know this or can provide evidence?&amp;quot;  1. Everything that the speaker asserts or implies is true unless otherwise explicitly stated.</Paragraph>
    <Paragraph position="9"> Motivation: &amp;quot;can I say this?&amp;quot; 1. Everything that the speaker wants to know or wants the partner to do is motivated except if the speaker cmmot take the initiative on it.</Paragraph>
    <Paragraph position="10"> 2. Everything that addresses what the partner wanted to know or wanted the speaker to do is motivated, except if the speaker emmot disclose the information or do the act.</Paragraph>
    <Paragraph position="11"> 3. Everything that is related to CC is motivated if not already known.</Paragraph>
    <Paragraph position="12"> 4. Everything that informs of inconsistency is motivated if not already known.</Paragraph>
    <Paragraph position="13"> Consideration: &amp;quot;may I say this?&amp;quot; 1. If the partner's goal cammt be fulfilled (presuppositions are false, facts contradictory, no information exists), it is considerate to inform why (explain, compensate, initiate repair).</Paragraph>
    <Paragraph position="14"> 2. If the response would repeat previous information, it is considerate to leave this implicit unless the information is assigned a special emphasis.</Paragraph>
    <Paragraph position="15"> 3. If the partner's response is unrelated, it is considerate to inform of the irrelevance, given that the speaker has unfulfilled goals.</Paragraph>
    <Paragraph position="16"> 4. \[f the partner did not request a piece of related  information, it is considerate to include this explicitly in the response, given that the speaker intends to close the topic.</Paragraph>
    <Section position="1" start_page="599" end_page="601" type="sub_section">
      <SectionTitle>
3.1 Example
</SectionTitle>
      <Paragraph position="0"> Consider the following sample dialogue where tile system's task is to provide service information to the user: Uh I need a car.</Paragraph>
      <Paragraph position="1">  $1: Do yon want to buy or rent one? Ui: Rent.</Paragraph>
      <Paragraph position="2"> $2: Where? U3: In Bolton.</Paragraph>
      <Paragraph position="3"> $3: OK. ttere are the car hire companies in Bolton: ....</Paragraph>
      <Paragraph position="4">  The analysis of the first user contribution U1 is given in Fig. 5. The content of the user's c-goal is inferred from the World Model which says that 'needing a car' can be interpreted as 'wanting to have a cl~r'.</Paragraph>
      <Paragraph position="5">  NEW INPO: needE(n,u,c), user(u), car(c) USER C-GOAL: want(u, want(s, know(s, \[want~e E(h, u, e )\]) )) CENTRAL CONCEPT: needE(n,u,c) EXPRESSIVE ATTITUDES: intention: user intend that system know P: want(u, know(s,\[needE(n,u, c ), user(u), car(c)\])) assumptions: user know that system not know P: know(u, not know(s,\[needE(n,u,d, user(u),car(e)\])) EVOCATIVE ATTITUDES: intention: user intend that system intend that system know P: want(u, want#, know(s, \[.eed E(n, u, c ), user(u ), ear(c)\]))) want(u, want(s, know(s,\[wantHave E(h,u,c )\], user(u ),~a,'(~ )\]) ) )  In the beginning of the dialogue the system has no unfulfilled goals, and its role as an obedient information provider does not allow it to have the initiative. Moreover, any contribution is trivially unrelated to the previous topic, since no previous topic exists. According to the Joint Purpose rule (2), the user's c-goal is thus adopted, and the system also takes the initiative, since the user contribution is non-expected (an information seeker is expected to start with a question or a request). The joint purpose becomes new-indir-request with &amp;quot;user wants to have a car&amp;quot; as the content, i.e. the communicative strategy is to share the user's want to have a car, and check if this want can be satisfied within the Application Model. The system cannot provide the user with a car, but it can provide information about the services that, enable the user to have a car. Application Model lists car hire companies and car garages as possible services, so the communicative goal is formulated as to know which is the preferred service. The services are associated with renting or buying cars, thus the disjunction is realised as 5'1. The system responses $2 and 5&amp;quot;3 are based on the same strategy baclcto: the system 'goes back' to adopt the user's previous unfulfilled goal and tries to satisfy this in the updated context. 4 However, they carry different c-goals due to different specification in the Application Model: $2 aims at narrowing down the database search, 5,3 completes the original task. Finally, the communicative obligation Consideration (4) requires that the application service (car hire company) and loca-tion (Bolton) are explicitly expressed in $3 before the list of services.</Paragraph>
      <Paragraph position="6">  maritally related, and the system has the initiative and unfulfilled goals, at least one based on the original task to provide information.</Paragraph>
    </Section>
  </Section>
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