<?xml version="1.0" standalone="yes"?>
<Paper uid="E99-1039">
  <Title>New Museums Site</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Several authors have highlighted the importance of using defaults in the representation of linguistic knowledge, in order to get linguistically adequate descriptions for some natural language phenomena ((Gazdar, 1987), (Bouma, 1992), (Daelemans et al, 1992), (Briscoe, 1993)). Defaults have been used in the definition of inflectional morphology, specification of lexical semantics, analysis of gapping constructions and ellipsis among others. In this paper we use defaults to structure the lexicon, concentrating on the description of verbal subcategorisation information.</Paragraph>
    <Paragraph position="1"> The issue of how to organise lexical information is especially important when a lexicalised formalism like Categorial Grammar (CG) or Head-Driven Phrase Structure Grammar (HPSG) is employed, since the burden of linguistic description is concentrated in the lexicon and if lexical entries are organised as unrelated lists, there is a significant loss of generalisation and an increase in redundancy. Alternatively, it is possible to use inheritance networks, which provide representations that are able to capture linguistic regularities about classes of items that behave similarly. This idea is employed in Pollard and Sag's (1987) sketch of an HPSG lexicon as a monotonic multiple orthogonal inheritance type hierarchy. However, this work fail to make use of defaults, which would significantly reduce redundancy in lexical specifications and would enable them to elegantly express sub-regularities (Krieger and Nerbonne, 1993). In this paper we demonstrate that using default unification, namely the order-independent and persistent version of default unification described in (Lascarides et al, 1996b) and (Lascarides and Copestake, 1999), to implement a default inheritance network results in a fully declarative specification of a lexical fragment based on Pollard and Sag's (1987), but that is both more succinct and able to express elegantly linguistic sub-regularities, such as the marked status of sub-ject control of transitive subject-control verbs.</Paragraph>
    <Paragraph position="2"> In section 2, a brief description of the use of defaults and YADU is given. In section 3, we present the results of representing the proposed lexical fragment in terms of default multiple inheritance networks. Finally, we discuss the results achieved and future work.</Paragraph>
  </Section>
class="xml-element"></Paper>