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<Paper uid="W98-1414">
  <Title>Institut fiir Wissensund Sprachverarbeitung -Abstract</Title>
  <Section position="2" start_page="0" end_page="128" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> When a coherence relation ties two adjacent portions of text together, it is often lexically signalled on the linguistic surface with a suitable word--most Often a conjunction, but also a preposition, a prepositional phrase or an adverb \[Quirk et al. 1972\]. The set of words from these grammatically heterogeneous classes that can signal coherence relations we call discourse markers. For example, :the CONCESSION relation in English can be signalled with the subordinator although, the adverb Still, the preposition despite, and a number of other words.</Paragraph>
    <Paragraph position="1"> For most coherence relations, language offers quite a variety of such markers, as several studies Of individual relations have demonstrated (see references in Section 2). Accordingly, from the generation perspective, a serious choice task arises if the produced * text is not only to simply signal :the coherence relation, but moreover to reflect pragmatic goals, stylistic considerations, and the different connotations markers have. The importance of these factors was stressed by Scott and de Souza \[1990\], who gave a number of informal heuristics for when and how to signal the presence of coherence relations in text. Fleshing out the choice task in order to come up with a computational model, though, reveals two sources of difficulty.</Paragraph>
    <Paragraph position="2"> For one thing, in addition to syntactic variety, the precise semantic and pragmatic differences between similar markers can be quite difficult to determine. For instance, the CONCESSION markers although and even though differ merely in emphasis; the CAUSE markers because and since differ in whether they mark the following information as given or not; the German CAUSE markers weil and denn differ in the illocution type of the conjuncts (proposition versus statement). Second, ,Complete address: Otto-von-Guericke Universit~it Magdeburg, IWS/FIN, Universit~tsplatz 2, 39106 Magdeburg, Germany; email: grote@iws, cs.tmi-magdeburg, de &amp;quot; : tComplete address: Technische Universit~t Berlin, Fachbereich Inforraatik, Projektgruppe KIT, Sekretariat FR 6-10, Franklinstr. 28/29, 10587 Berlin, Germany; email: stedeecs.tu-berlin.de</Paragraph>
    <Paragraph position="4"> the dependencies between marker choice and other generation decisions are rather intricate. The idea of avoiding them is, presumably, the reason for the simplistic treatment of marker choice in typical generators to-date: They regard discourse markers as mere consequences of the structural decisions, hence do not perform any choice. We wish to demonstrate, however , that this strategy, which is typical for dealing with closed-class lexical items in general, is too great .a simplification in these cases.</Paragraph>
    <Paragraph position="5"> In this paper, we propose to use a discourse marker lexicon as a declarative resource for the sentence planning stage of the text generation process. The paper is organized as follows. Section 2 examines the role of discourse markers in NLG and reviews the state of the art. Section 3 briefly summarizes the ideas on sentence planning that have arisen in the past few years and argues that for a sophisticated treatment of discourse marker choice, a dedicated lexicon is to be used as one information resource in sentence planning. Section 4 *introduces the discourse marker lexicon we are currently developing, and Section 5 describes how this lexicon can be usefully employed in the sentence planning phase to realize more flexible marker production.</Paragraph>
    <Paragraph position="7"/>
  </Section>
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