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<Paper uid="C86-1069">
  <Title>MACHINE LEARNING OF MORPHOLOGICAL RULES BY GENERALIZATION AND ANALOGY</Title>
  <Section position="2" start_page="292" end_page="292" type="concl">
    <SectionTitle>
5. Unsolved Problems
</SectionTitle>
    <Paragraph position="0"> - The Formalism which PRISM uses For the representation of the instructions is designed For the description of graphemie changes at: tile beginning and/or at the end of a word. Thus this Formalism Js inadequate For the description oPS changes in the interior of a word. These, however, occur more rarely t_han t~he changes at: the beginning or at the end. A solution to this problem, which could consist. in the design of a new Formalism whose expressions could also be \].earned automatically, has not as yet: been Found.</Paragraph>
    <Paragraph position="1"> PRISM cannot recognize exceptions in a learning corpus and treat them adequately. If, for instance, the learning corpus in Figure 1 would also contain the pair ('goose', &amp;quot;geese), PRISM would infer the prefixal substitution instruction &amp;quot;goo&amp;quot; -&gt; &amp;quot;gee'/# and insert it in the set of instructions shown in Figure 4 before instruction (1).</Paragraph>
    <Paragraph position="2"> Furthermore PRISM would infer the suf-Fixal instruction &amp;quot; ' -&gt; ' &amp;quot;/'ose&amp;quot; # and insert it before instruction (3). IF this new set of instructions is applied to the nouns &amp;quot;good', &amp;quot;goodness&amp;quot; and &amp;quot;goon&amp;quot; the incorrect plurals &amp;quot;geeds', &amp;quot;geednesses&amp;quot; and &amp;quot;gowns' are generated. - It would be preferable for PRISM to identify exceptions as such and store them in a list of exceptions instead of inferring overgeneralizing instructions from them.</Paragraph>
    <Paragraph position="3"> If a set of instructions is linguistically inadequate, the user of PRISM must First make the learning corpus more representative by adding suitable examplea. Then he must activate the learning component of PRISM ~hich infers a totally new set of instructions. Perhaps it ~ould be better if PRISM could infer new instructions only From the ne~ examples and then synthesize these ne~ instruc-Lions wiLh the fiormerly inferred and lJnguisLieally inadequaLe JnsLrueLions Lo give a new, more adequaLe seL off instrucLions. null</Paragraph>
  </Section>
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