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<Paper uid="E87-1024">
  <Title>e Parsing into Discourse Object Descriptions</Title>
  <Section position="2" start_page="0" end_page="140" type="intro">
    <SectionTitle>
INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> The LINLIN-project is concerned with the development of general-purpose natural language interfaces (NLIs) to computer software with special emphasis on communication in Swedish. A useful general-purpose NLI must meet a var/ety of requirements, a number of which concern communicative ability. The communicative abilities of as NLI are necessarily restricted by the limitations of existing techniques, but can also be purposely restricted to enhance transparency. It is not certain that the linguistically more competent NLI is the most useful one, e.g. if its behaviour appears idiosyncratic to the user. In any case, the language of an NLI is a language designed (and is in that respect not a natural language) so there are many questions to be answered about how it should be designed, both in terms of how it should function as a vehicle of communication and in terms of internal representations and procedures.</Paragraph>
    <Paragraph position="1"> As for the first aspect we are conducting a series of simulations to fred out what communicative abilities an NLI should have (Dahlb~k&amp;J~neson, 1986), but meanwhile we are assuming that LINLIN should meet the following demands: it should have a fair knowledge of the structure of Swedish words, clauses and utterances, an s This work is part of the project Analysis and Generation of Natural-Lan~,ruage Texts supported by the National Swedish Board of Technical Development.</Paragraph>
    <Paragraph position="2"> extendable lexicon, an extendable knowledge of object types, an ability to cope with directives, questions and assertions as they relate to the current background system(s) and a restricted ability to engage in a dialogue with the user.</Paragraph>
    <Paragraph position="3"> The dialogue capabilities of LINLIN are primarily designed for the following purposes: (a) to enable the user to make explicit and implicit cross-references between utterances, e.g. by using pronouns and ellipsis; (b) to allow the user to build commands incrementally; (c) to ask the user for clarifications and other information that the system might need, and (d) to provide help for the user. In this paper some consequences of these demands for the representation and interaction of various types of knowledge that the system needs are considered. The main ideas are t~e following: (1) The content of user inputs is preferably represented as a structure of Discourse Object Descriptions (DODs) which relate in various ways to objects of the universe of discourse. (2) Different types of knowledge, including object type knowledge and knowledge of the current state of the discourse must be used and integrated in the construction of an interpretation. (3) To ensure generality and in contrast to the entity-oriented parser of Hayes (1984), the grammatical knowledge is not exclusively tied to object type definitions but stored separately. (4) Knowledge about the discourse status of objects is also a kind of general knowledge that must be kept separate from object type definitions. (5) In a constraint-based parsing process the grammatical descriptions and the content descriptions can be built in tandem, sometimes with the syntax in control and sometimes with the object knowledge in control. This allows us to diminish the role of the syntactic part of the parsing to recognition of significant structural patterns, using semantic and pragmatic knowledge for the resolution of structural ambiguities such as PP-attachment.</Paragraph>
    <Paragraph position="4"> The first background system that LINLIN will work on is a group calendar. As the pilot Version of LINLIN is only in its initial stages my arguments will mainly be theoretical, while the practicality of the proposed ideas remains to be proven.</Paragraph>
  </Section>
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