<?xml version="1.0" standalone="yes"?>
<Paper uid="P96-1004">
  <Title>Morphological Cues for Lexical Semantics</Title>
  <Section position="6" start_page="28" end_page="29" type="evalu">
    <SectionTitle>
5 Evaluation
</SectionTitle>
    <Paragraph position="0"> Good surface cues are easy to identify, abundant, and correspond to the needed lexical semantic information (Hearst (1992) identifies a similar set of desiderata). With respect to these desiderata, derivational morphology is both a good cue and a bad cue.</Paragraph>
    <Paragraph position="1"> Let us start with why it is a bad cue: there may be no derivational cues for the lexical semantics of a particular word. This is not the case for other surface cues, e.g., distributional cues exist for every word in a corpus. In addition, even if a derivational cue does exist, the reliability (on average approximately 76 percent) of the lexical semantic information is too low for many NLP tasks. This unreliability is due in part to the inherent exceptionality of lexical generalization and thus can be improved only partially.</Paragraph>
    <Paragraph position="2"> However, derivational morphology is a good cue in the following ways. It provides exactly the type of lexical semantics needed for many NLP tasks: the affixes discussed in the previous section cued nominal semantic class, verbal aspectual class, antonym relationships between words, sentience, etc. In addition, working with the Brown corpus (1.1 million words) and 18 affixes provided such information for over 2500 words. Since corpora with over 40 million words are common and English has over 40 common derivational affixes, one would expect to be able to increase this number by an order of magnitude.</Paragraph>
    <Paragraph position="3"> In addition, most English words are either derived themselves or serve as bases of at least one derivational affix. 3 Finally, for some NLP tasks, 76 per- null cent reliability may be adequate. In addition, some affixes are much more reliable cues than others and thus if higher reliability is required then only the affixes with high precision might be used.</Paragraph>
    <Paragraph position="4"> The above discussion makes it clear that morphological cueing provides only a partial solution to the problem of acquiring lexical semantic information.</Paragraph>
    <Paragraph position="5"> However, as mentioned in section 2 there are many types of surface cues which correspond to a variety of lexical semantic information. A combination of cues should produce better precision where the same information is indicated by multiple cues. For example, the morphological cue re- indicates telicity and as mentioned above, the syntactic cue the progressive tense indicates non-stativity (Dorr and Lee, 1992). Since telicity is a type of non-stativity, the information is mutually supportive. In addition, using many different types of cues should provide a greater variety of information in general. Thus morphological cueing is best seen as one type of surface cueing that can be used in combination with others to provide lexical semantic information.</Paragraph>
  </Section>
class="xml-element"></Paper>