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<Paper uid="E85-1013">
  <Title>THE PERPETUAL MOTION MACHINE IS THE BANE OF LIFE IN A PATENT OFFICE A MAN I JUST MET LENT ME FIVE POUNDS</Title>
  <Section position="16" start_page="91" end_page="91" type="concl">
    <SectionTitle>
PREPOSITION SEMANTICS: PREPLATES
</SectionTitle>
    <Paragraph position="0"> In fact rule A was intentionally naive: it was designed to demonstrate (as against Shubcrt's claims in particular) the wide coverage of the data of a single semantics-based rule, even if that required additional, hard to motivate, semantic information to be given for action and states. It was stated in a verb-based lexical preference mode simply to achieve contrast with the other systems discussed.</Paragraph>
    <Paragraph position="1"> For some years, it has been a principle of preference semantics (e.g. WilLS 1973, 1975) that attachment relations of phrases, clauses etc. are to be determined by comparing the preferences emanating from all the entities involved in an attachment: they axe all, as it were, to be considered as objects seeking other preferred classes of neighbors, and the best lit, within and between each order of structures built up, is to be found by comparing the preferences and finding a best mutual fit. This point was made in (Wilks 1976) by contrasting preference semantics with the simple verb-based requests of Riesbeck's (1975) MARGIE parser. It was argued there that account had to be taken of both the preferences of verbs (and nouns), and of the preferences cued from the prepositions themselves.</Paragraph>
    <Paragraph position="2"> Those preferences were variously called paraplates (WilLS 1975), preplates (Bognraev 1979) and they were, for each preposition sense, an ordered set of predication preferences restricted by action or noun type. {WilLS 1975} contains examples of ordered paraplate stacks and their functioning, but in what follows we shall stick to the preplate notation of (Huang 1984b).</Paragraph>
    <Paragraph position="3"> We have implemented in CASSEX (see WilLS, Huang and Fass, 1985) a range of alternatives to Rule A : controlling both for &amp;quot;low&amp;quot; and &amp;quot;high&amp;quot; default; for examination of verb preferences first (or more generally those of any entity which is a candidate for the root of the attachment, as opposed to what is attached) and of what-is-attached first (i.e. prepositional phrases). We can also control for the application of a more redundant form of rule where we attach preferably on the conjunction of satisfactions of the preferences of the root and the attached (e.g. for such a rule, satisfaction would require both that the verb preferred a prepositional phrase of such a class, and that the prepositional phrase preferred a verb of such a class}.</Paragraph>
    <Paragraph position="4"> In (Wilks, Huang &amp; Fass 1985) we describe the algorithm that best fits the data and alternates between the use of semantic information attached to verbs and nouns (i.e. the roots for attachments as in Rule A) and that of prepositions; it does this by seeking the best mutual fit between them, and without any fall back to default syntactic rules like (i) and (ii).</Paragraph>
    <Paragraph position="5"> This strategy, implemented within Huang's (1984a, 1984b) CASSEX program, correctly parses all of the example sentences in this paper. CASSEX, which is written in Prolog on the Essex GEC63, uses a definite clause grammar (DCG) to recognize syntactic constituents and Preference Semantics to provide their semantic interpretation. Its content is described in detail in (WilLS, Huang &amp; Fass 1985) and it consists in allowing the preferences of both the clause verbs and the prepositions themselves to operate on each other and compete in a perspicuous and determinate manner, without recourse to syntactic preferences or weightings.</Paragraph>
  </Section>
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