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<Paper uid="C88-1039">
  <Title>Semantic Interpretation of Pragmatic Clues: Connectives, Modal Verbs, and Indirect Speech Acts</Title>
  <Section position="1" start_page="0" end_page="191" type="abstr">
    <SectionTitle>
Abstract
</SectionTitle>
    <Paragraph position="0"> Much work in current research in the field of semantic pragmatic analysis has been concerned with the interpretation of natural language utterances in the context of dialogs. In this paper, however, we will present methods for a primary pragmatic analysis of single utterances. Our investigations involve problems which are not currently well understood, for example how to infer the speaker's intentions by using interpretation of connectives and modal verbs.</Paragraph>
    <Paragraph position="1"> This work k,; part of the joint project WlSBER which is supported by the German Federal Ministery for Research and Technology. The partners in the project are: Nixdorf Computer AG, SCS GmbH, Siemens AG, the University of Hamburg and the University of Saarbrticken.</Paragraph>
    <Paragraph position="2"> Introduction Much work in current research in the field of semantic pragmatic analysis has been concerned with the interpretation of ~Latural language utterances in the context of dialogs, e.g., determining the speaker's goals \[Allen 83\], deriving beliefs of one agent about another \[Wilks/Bien 83\], and planning speech acts \[Appelt 85\]. In this paper, however, we will present methods for a primary pragmatic analysis of ,~Jingle utterances to construct user model entries which are the starting point for the higher level inference processes just mentioned. Our investigations involve problems which are not currently well understood, for example, how to infer the speaker's intentions by using interpretation of connectives and modal verbs.</Paragraph>
    <Paragraph position="3"> Our work is a part of the natural language consultation system WISllER \[Bergmann/Gerlach 87\]. Consultation dialogs require a much wider class of utterances to be understood than other applications (e.g., for data base interface). In advisory dialogs wants and beliefs play a central role. Although a consultation system must be capable of handling the linguistic means which are used for expressing those attitudes, problems of how to treat modal verbs have received little attention in artificial intelligence and computational linguistics.</Paragraph>
    <Paragraph position="4"> The interpretation processes described in this paper work with our aemantic representation !anguage IRS \[Bergmann et. al. 87\] and generate entries for the user model Representations of utterances in IRS still contain uninter preted linguistic features such as modal verbs, modal hedges, connectives, and tense information. We are pre senting methods for deriving the meaning of these features as they occur in utterances: transforming idiomaticallyused indirect speech acts, interpreting connectives in compound sentences, and resolving ambiguities in the meaning of modal verbs by using, i.a., temporal restrictions. The last chapter sketches the technical means used by these processes, i.e., the semantic representation language, the way rules are encoded, and the asscrtional knowledge base containing the user model.</Paragraph>
    <Paragraph position="5"> Fig. 1 shows the different stages of the interpretation process. First, if a connective is found, the analysis process breaks up the sentence into separate propositions, in the next step idomatically-used indirect speech acts are transformed into a direct question. The propositions are then interpreted independently during the modal verb analysis which creates one or more propositional attitudes for each proposition. These interpretations arc then related, depending on the natural language connective.</Paragraph>
    <Paragraph position="6"> Finally, after inferring the appropriate time intervals from verb tense, the sentence type is used to derive the propositional attitudes which are entered into the user model.</Paragraph>
    <Section position="1" start_page="0" end_page="191" type="sub_section">
      <SectionTitle>
Transformation of Idiomatically-Used Indirect
Speech Acts
</SectionTitle>
      <Paragraph position="0"> Speakers often use indirect speech acts because they want to express politeness or uncertainty. Examples are : &amp;quot;Could you please tell me which bonds have the highest interest rate?&amp;quot;, &amp;quot;i'd like to know which...&amp;quot;, &amp;quot;I do not know which....&amp;quot; We believe that for appropriately handling such an idiomatic use of indirect speech acts in a consultation system it is admissible to transform such utterances into a simplified form - the corresponding direct quest;~n.</Paragraph>
      <Paragraph position="1"> Therefore the first step in our semantic-pragmatic interpretation is mapping the different ways of asking questions onto one standard form which is the formal representation of the equivalent direct question.</Paragraph>
      <Paragraph position="2"> Fig. 2 shows the ru~e which applies to the idiom &amp;quot;I do not know whether X.&amp;quot; and transforms it into the represen tation of the direct speech act &amp;quot;X ?&amp;quot; The rule formalism will be described in detail later.</Paragraph>
      <Paragraph position="3">  Durin$&amp;quot; that transformation process we do not loose any information which might be relevant to the dialog control component of the system (not described in this paper).</Paragraph>
      <Paragraph position="4"> Before answering any question - direct or indirect - the system has to check whether it is able to answer that question. If this is not the ease the user must be informed about the limitations of the system's competence, anyway.</Paragraph>
      <Paragraph position="5"> This argumentation is similar to that of \[Ellman 83\], who argues that it is not relevant whether an utterance is a request or an inform as long as the hearer can detect the speaker's superordinate goals.</Paragraph>
      <Paragraph position="6">  The transformation of indirect speech acts works on the semantic level by applying rules which specify formal transformations of semantic representations of sentences.</Paragraph>
      <Paragraph position="7"> In this our approach differs from that taken in UC \[Wilensky et. al. 84 and ZernikfDyer 85\] where a phrasal lexicon is used and the semantic interpretation of idioms is done during the parsing process.</Paragraph>
      <Paragraph position="8"> Interpretation of Modal Verbs An adequate treatment of modal verbs is necessary for determining the attitudes of the speaker concerning the state of affairs expressed by the proposition he is asserting. 1) The main problem in interpreting modal verbs is their typical ambiguity, e.g.,  (1) Mein Sohn sod viel Geld haben.</Paragraph>
      <Paragraph position="9">  In English the two readings are: 'My son is supposed to have a lot of money.' VS.</Paragraph>
      <Paragraph position="10"> 'I want my son to have a lot of money.' Our rules for disambiguating the different readings are based on information which is stored in the semantic representation of the utterance: information about semantic categories of the subject of the modal verb (e.g., ANIMATE, GENERIC, DEFINIT\]O, the relation between the time expressed by the modal verb and the time of the proposition and whether the proposition denotes a state or an event.</Paragraph>
      <Paragraph position="11"> (2) Ich habe 10000 Mark geerbt und m6chte das Geld ir~ Wertpapieren anlegem Sic sollen eine Laufzeit yon vier Jahren haben.</Paragraph>
      <Paragraph position="12"> 'I have inherited 10000 Marks and would like to invest the money in securities.' Two readings of the second sentence: &amp;quot;they are supposed to have a term of fbur yea,'s.' VS.</Paragraph>
      <Paragraph position="13"> Whey should have a term of four years.' In the first reading of the second sentence the entry for the user model must contain the proposition embedded in a belief context, while the second reading must lead to an entry under speaker's wants. In order to resolve this ambiguity, the rules compare the time of the proposition with the tense of the modal verb. For example, if the tense of the modal verb is present and the time of the proposition is sometime in the future, the system decides that the &amp;quot;want&amp;quot; reading is appropriate. The problem in our example is to determine the time of the proposition: We have only the information of tense haben (to have) which is a present infinitive and might also denote a future state. Hence the system tries to final out whether the object of the proposition appears in a Want context of the speaker. This is the case as is clear from the previous utterance ... and I wan$ to invest the money in securities and therefore the ~y~tem decides to put the propesition of the ~c~nd sent~t~e into the user's want ~ontext as well. (Even if the second utterance is taken to be a belief of the ~peaker, the fact that it is cited in this context is sufficient to infer that it is also a want, why else should the speaker cite this fact in connection with his decision to invest in securities?) 1) For the semantics of English modal verbs, which is quite different from the German, see \[Boyd/Thorne 69\]. For German modal verbs see \[Brttnner/Redder 83\], \[Rei~wvin 77\], \[Spr~nge r 88\].</Paragraph>
      <Paragraph position="14"> Usually the user's questions are interpreted as user wants to knowp (or more formally: (WANT USER (KNOW USER P))), where ~ th;notes the propositional content of the question. For example, (3) K0nnen Pfandbriefe mehr als 7% Rendite haben? 'C~n bonds have an interest rate of more then 7%?' is interpreted as: the user wants to know whether the proposition is true, which means in our example, taking into account the modal verbk6nnen, whether it is possible for bonds to have an interest rate ofmore then 7 %.</Paragraph>
      <Paragraph position="15"> One problem arises when the modal verb sollen occurs in a question. Normally it is interpreted as indicating a want, e.g., (4) Soil ich das Fenster schliegen? 'l\]hould I close the window?' Here the speaker wants to know, whether there is some other pers~m (probably the hearer), who wants the proposition to be true. But this interpretation doesn't make any sense in a consulting dialog. Ina consultation the speaker is not interested in the wants of the advisor, e.g., (5) Soll ich Pfandbriefe mit 5% Rendite kaufen? 'l~hould I buy bonds which have an interest rate of 5 %?' Rather than inquiring about someone else's wants, as in (4), the speaker is interested in a recommendation:</Paragraph>
    </Section>
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