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<Paper uid="E89-1019">
  <Title>LEXICAL ACQUISITION IN THE CORE LANGUAGE ENGINE</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> The SRI Core Language Engine (CLE; A1shawi et al, 1988a,b) is a domain independent system for translating English sentences into formal representations of their literal meanings which are capable of supporting reasoning. It is designed to be used as a major component of interactive advisor systems such as interfaces to database management systems and diagnostic expert systems. The main contribution of the CLE is intended to be substantial coverage of English constructions in both syntax and semantics that is well motivated and hence extensible.</Paragraph>
    <Paragraph position="1"> The CLE makes use of three main types of lexicon entry.</Paragraph>
    <Paragraph position="2"> A syntactic entry for a word consists of one or more complex categories, each specified by a principal category symbol augmented by a set of constraints on the values of syntactic features. Such categories also appear in the CLE's grammar, and matching and merging of the information encoded in them carried out by unification during parsing.</Paragraph>
    <Paragraph position="3"> Word sense entries for words are specified in the same way, but involve semantic as well as syntactic features.</Paragraph>
    <Paragraph position="4"> Semantic interpretation, which takes place in tandem with parsing, works by unification of feature values in word sense entries and semantic interpretation rules.</Paragraph>
    <Paragraph position="5"> Sortal (selectional) restrictions are defined for logical form predicates (i.e. word senses). After possible semantic interpretations are constructed, the CLE applies these restrictions with reference to a user-definable hierarchy of sortal classes, to reject any interpretations in which the sort expected by some argument - 137 of a predicate is inconsistent with that of the object filling that argument. null The CLE lexical acquisition tool VEX (for Vocabulary EXpander) allows the creation of CLE lexicon entries by users with knowledge both of English and of the application domain, but not of linguistic theory or of the way lexical entries are represented in the CLE. It asks the user for information on the grammaticality of example sentences, and for selectional restrictions on arguments of predicates, and writes to disc a set of instructions that can immediately be used by the CLE to create appropriate lexical entries automatically in main memory.</Paragraph>
  </Section>
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