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<Paper uid="C92-4186">
  <Title>EBL2: AN APPROACH TO AUTOMATIC LEXICAL ACQUISITION</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> A persisting trend in unification-based approaches to natural language processing is to incorporate large quantirAes of information in the lexicon, informatio,i that has traditionally resided in the gran,mar rules.</Paragraph>
    <Paragraph position="1"> Acquiring a lexicon has thus becolne a diflicull and time consuming txsk, even for moderately sized lex ira. In addition to this, an.',' natural language processing system intended for serious applications must include a large lexicon -- several thousands of words or more is commonly considered a minimun~ size which adds even more to the complexity of the lu'oblem. In view Of this, tools for lexical acqusition are not only desirable they become a necessity.</Paragraph>
    <Paragraph position="2"> Most. approaches to this problem hay,' been *Department of (.\]onlpuler ,~lld S)'steRIS ScieIIC('S, S\[ock. hohn University, Electrnm 23(/, S - 16.t ,In \]&lt;.ISTA, Sweden. I NLP-group, Swedish hmtitute tff Computer Science, Box 1263, S 16.1 28 KIST&amp; Stockhohn, Sweden.</Paragraph>
    <Paragraph position="3"> to construct a range of tools that require varinus degrees of inleraclive support when new lexical entries are created, either from raw text material (as ill e.g., \['frost &amp; Bnchberger 86, Grosz ct al 87, Wilensky 90\] and tile early work by Zernik \[Zernik ~(,&amp;quot; Dyer 85, Zernik 87\]), or from machine readable dictionaries (see e.g., \[Bognraev el al 87, ('.alzolari &amp;&amp;quot; Bindi 90\]). Although interactive tools |or h'xical acquisition greatly simplifies tile task of constructing a lexicon, it. is desirable to go oue step further and fully remow&amp;quot; the need for user interaction. null One of the first systems that aimed at constructing lexica\] entries automatically from raw text was Granger's FOUL-U'P system \[Granger 77\]. FOUL-UP extended a lexicon by referring restrictions placed on unknown words by instantiating scripts that matched the sentences containing the nnknown words. This I)uilt on a immber of assumptions which in general do nol bold, in particular: that all the information needed to create all entry is contained ill one text: that no nmrphological information is needed; tha~ specific (hand-coded) scripts covering the domain can be made available in advance, hi one of the later approaches to automatic lexical acquisition from raw text, \[dacobs ,to Zernik 88\] have shown the need to consult a variety of knowledge sources such ~s morphological, syntactic, semantic, and contextual knowledge when determining a new lexical entry.</Paragraph>
    <Paragraph position="4"> This paper describes an automatic nlethod to acquire new lexical entries by using analytical learning in coml,inalion wit.h strategies used in an existing interactive tool for lexical acquisition (VEX \[Carter 89}). In the process of constructing a lexical entry. the system combines several different sources of information: the underlying NL system (CLE, \[Alshawi red.) 92\]) will contribute information on syntactically and semantically permissible phrases and on tile rules for inIlectional nmrl)hology. The corpus wilt contrihute information on which of these constructions actually occur. This information is combined with tile the linguistic knowledge encoded in the interactive lexical acquisition tool to infer lexical entries for unknown words m the text.</Paragraph>
    <Paragraph position="5"> The rest of Ihe paller is laid out as follows: Section :2 contains information al)out the various elements on which the method is based. Section 3 de-AcrEs DE COLING-92, NANTES, 23-28 Aot)'r 1992 1 l 7 2 PRec. el: COLING-92, NANTES, AUG. 23-28, 1992 scribes the method itself and Section 4 reports on For these &amp;quot;paradigm words&amp;quot; only, the complete set the current state of the implementation, of feature vahles is explicitly specified.</Paragraph>
  </Section>
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