<?xml version="1.0" standalone="yes"?>
<Paper uid="A88-1008">
  <Title>HANDLING SCOPE AMBIGUITIES IN ENGLISH</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> Natural languages contain a variety of &amp;quot;logical operators&amp;quot; which interact with each other to give rise to different types of ambiguity. The logical operators recognized by the scoping program include quantifiers, coordinators and negation, which are initially &amp;quot;unscoped&amp;quot; and must therefore be moved into position by the program, and adverbs, predicates and connectives (such as if-then). At the moment, other operators such as tense, aspect and modals are left in place and therefore assume innermost scope. There is some evidence that the handling of the scoping of quantifiers relative to such operators may require special treatment (eg. Fodor 1970; Enc 1981; S aarinen 1983).</Paragraph>
    <Paragraph position="1"> Three simple examples will illustrate some different types of scope ambiguity and their representation in an informal first order predicate logic, using restrictions on quantifiers and an infix notation for sentential formulas. The meanings of the different interpretations should be clear. For example, (4) may mean that John didn't meet either Jane or Mary (5) or that he didn't meet at least one of them (6). Further examples are given in Hurum &amp; Schubert (1986) and Hurum (1987). Some alternative proposals for representing scope ambiguities are also discussed in the latter.</Paragraph>
    <Paragraph position="2">  (1) Someone loves everyone (2) (3x:person (Vy:person \[x loves y\])) (3) (Vy:person (3x:person \[x loves y\])) (4) John didn't meet Jane or Mary (5) --,\[\[John met Jane\] v \[John met Mary\]\] (6) \[--,\[John met Jane\] v ~\[John met Mary\]\] (7) Someone always comes late (8) (3x:person (always \[x comes late\])) (9) (always (3x:person \[x comes late\]))  Until quite recently, designers of natural language understanding systems have given little attention to the problem of dealing with scope ambiguities. Two of the earliest attempts to incorporate quantifier scoping into natural language understanding systems in ,an integral way are described in Woods (1978) and Dahl (1979). Some more recent scoping algorithms are presented in McCord (1981), Warren &amp; Pereira (1982), Hobbs (1983), Saint-Dizier (1985) and Hobbs &amp; Shieber (1987).</Paragraph>
    <Paragraph position="3"> While each of these algorithms introduces some new features, certain problems, such as the scoping of coordinators and the use of heuristics to select preferred readings, have generally been given little or no treatment. Some of the main features of the algorithm being discussed here are: (a) it handles ambiguities created by quantifiers, coordinators, negation and adverbs, ~ (b) it works bottom-up and left-to-right and generates the set of valid scoped readings in one pass, (c) it removes logically redundant readings as they are encountered during the process of scoping and (d) it uses domain-independent heuristics, during the scoping, to arrange the readings in an approximate order of preference.</Paragraph>
  </Section>
class="xml-element"></Paper>