<?xml version="1.0" standalone="yes"?>
<Paper uid="E93-1037">
  <Title>Resolving Zero Anaphora in Japanese</Title>
  <Section position="2" start_page="0" end_page="315" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Over the past years, schemes like Focusing and Centering have dominated computational approaches to resolving anaphora \[Sidner, 1983; Walker et al., 1990\]. Their success derives from the utility they have in identifying salient discourse entities such as topic and thereby locating the antecedent for an anaphor. But they all suffer from the problem of directionality; they process the text (the list of sentences) from left to right, picking out focus along the way and see if a anaphor corefers with a focus already encountered. With the one-way processing, forward-looking pronouns (cataphora) are not possible to resolve. Since Japanese has great tolerance with forward reference, a proper theory of zero pronouns should meet the problem of directionality.</Paragraph>
    <Paragraph position="1"> In what follows, we discuss some points about discourse segment and zero pronoun in Japanese. We begin by introducing the idea of discourse segment.</Paragraph>
    <Paragraph position="2"> Consider the pair:  (1) Taro-go sara&lt;i&gt;-wo dasi, Hanako nora plate ace prepare-and -go 02&lt;i&gt; ryori -wo morituketa.</Paragraph>
    <Paragraph position="3"> nora food acc arranged Taro prepared the plates, Hanako arranged food on them.</Paragraph>
    <Paragraph position="4"> (2) Taro -ga sara&lt;~&gt; -wo dasi, Hanako&lt;i&gt; -wa top 01&lt;i&gt; 02&lt;k&gt; ryori-wo morituketa.</Paragraph>
    <Paragraph position="5">  Taro prepared the plates, Hanako arranged food. Here, 02 represents a suppressed expression. It acts as an indirect object of the verb moritsuketa. 1 1 and 2 are morphologically identical except that 1 has ga (nominative marker) where 2 has wa (topic marker). But they differ widely in meaning:l implies that Hanako arranged food on the plates that Taro prepared, the reading 2 does not imply; in 2, 1Here and throughout, we intend the term 01 to represent a zero pronoun for the subject, 02 for the indirect object, and 03 for the direct object.</Paragraph>
    <Paragraph position="6">  Hanako could have arranged food on plates somebody other than Taro prepared. Now locating the difference will involve the notion of discourse segment. A discourse segment is defined as a set of sentences which appear in some region of text and which is delimited by a topic-particle wa. Thus 2 breaks up into two segments, a clause with Taro-ga and one with Hanako-wa;1, containing no wa-marked element, forms a segment by itself. Section 2.1 provides syntactic definitions for the discourse segment. Another important feature of discourse segment is that of complying with the Minimal Semantics Thesis (MST) \[Nomoto, 1992\], a functional property that makes a segment cohere. The MST says, 'Assume as identical any pair of zero pronouns if it is part of some segment and does not occur as arguments for the segment's predicate.' Thus any pair of zero pronouns that fall into the domain of discourse segment are taken to be coreferential, unless they occur for the same predicate. 2 Significantly, the MST is amenable to syntactic treatment.</Paragraph>
    <Paragraph position="7"> In addition, we make use of ~he empathy hierarchy to choose between coreference relationships admitted by the MST. We specify a predicate for the empathy hierarchy and resolve zero anaphora by unifying one predicate's empathy hierarchy with another which occurs in the same segment. Since unification is a non-directional operation, we are able to treat forward as well as backward reference.</Paragraph>
  </Section>
class="xml-element"></Paper>