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<Paper uid="W01-1612">
  <Title>nnotating Anaphoric and Bridging Relations with MMAX</Title>
  <Section position="3" start_page="1" end_page="2" type="intro">
    <SectionTitle>
2 Definition
</SectionTitle>
    <Paragraph position="0"> In general, anaphoric as well as bridging relations hold between specifying expressions. These are those expressions that specify (i.e. are used to refer to) a particular extra-linguistic entity. In what follows, we briefly discuss the approach of (Vieira &amp; Poesio, 2000) and present our own definition. Since (Vieira &amp; Poesio, 2000) address the problem of bridging annotation, they try to find an operational and easily applicable definition. This is the main motivation for choosing (Vieira &amp; Poesio, 2000) (and not e.g. (Clark, 1975), who introduced the term bridging) as the background of our discussion. In the following discussion, two features of pairs of specifying expressions will be important. The first one is cospecification (Sidner, 1983), also known as coreference, a relation holding between two or more specifying expressions which specify the same extra-linguistic entity. The second important feature is identity of the head noun. This feature is applicable to full NPs only and simply states that in a pair of NPs the head of each is realized by the same noun.</Paragraph>
    <Paragraph position="1"> Anaphor. In (Vieira &amp; Poesio, 2000), only those relations are classified as anaphoric in which both cospecification and identity of the head noun is given.</Paragraph>
    <Paragraph position="2">  Consequently, their rather strict definition contains but one type, which the authors call direct anaphor. In contrast to this, we take only cospecification to be a necessary condition for anaphor. In case that identity of the head noun is also given, we call this direct anaphor as well. We believe, however, that additional sub-types of anaphor should be defined depending on the type of the anaphoric expression. Along these lines, we further distinguish pronominal anaphors, and those in which the object specified by the second expression is standing in a conceptual IS-A (or hyponymhyperonym) relation to the object specified by the first one. Consider the NP [das Bauwerk] in the following example, which denotes a super-concept of [dem Geb&amp;quot;aude].</Paragraph>
    <Paragraph position="3"> Seit 1972 befindet sich das Romanische Seminar in [dem Geb&amp;quot;aude Seminarstrasse 3]. [Das Bauwerk] wurde 1847 [...] errichtet. (HTC010) Since 1972, the Romance Seminar is situated in [the building Seminarstrasse 3]. [The structure] was built [...] in 1847.</Paragraph>
    <Paragraph position="4"> Bridging. Due to their strict definition of anaphor, the term bridging is applied rather widely in (Vieira &amp; Poesio, 2000). First, those expressions are classified as bridging which cospecify with their antecedent, but which do so not by means of an identical, but a different head noun. Finally, also non-cospecifying expressions are classified as bridging as long as they stand in some lexical relation (i.e. hyponymy, meronymy or co-hyponymy) to their antecedent. The respective bridging sub-types are introduced by the authors accordingly. Our approach, in contrast, classifies as bridging only those expressions which are non-cospecifying and which stand in some conceptual relation to their antecedent. At this time, we consider the following relations to be relevant: cause-effect, partwhole, and entity-attribute, for which we give the following examples: Deshalb wurden [verschiedene Untersuchungen] [...] vorgenommen. [Das Ergebnis] (cause-effect) war die Erstellung von Leitlinien f&amp;quot;ur die gestalterische Behandlung des  It must be added here that (Vieira &amp; Poesio, 2000) consider definite NPs only, and in particular no pronouns. [Hortus Palatinus]. Danach plante man, [die Zwischenterasse] (part-whole) [...] wiederherzustellen. (HTC113) Therefore, [various examinations] [...] were conducted.</Paragraph>
    <Paragraph position="5"> [The result] (cause-effect) was the production of guidelines for the design of the [Hortus Palatinus]. After that, plans were made to restore [...] [the middle terrace] (part-whole). The Concept of Antecedence. In pairs of anaphoric or bridging expressions, one member is regarded as the antecedent of the other. In fact, the task of resolving such a relation is often identified with finding the antecedent. While there are certainly cases where it is possible to find exactly one antecedent to a given expression, there are also cases where this decision is not obvious. This is true for anaphoric as well as bridging antecedents: Consider the case of an NP that has been introduced into the universe of discourse, and that is referred back to anaphorically twice by means of a pronoun. We believe that it is not at all clear what is to be regarded as the antecedent of the second pronoun, since one could argue for the NP on the grounds of its semantic explicitness, or for the first pronoun on the grounds of its being the more recent cospecifying entity. The same is true with bridging expressions. In the example in Section 1, one could regard the pronoun [es] as the bridging antecedent of [der Haupteingang] as well.</Paragraph>
    <Paragraph position="6"> Preliminary Conclusion. Our definition of anaphor and bridging developed so far can be summed up as follows: Anaphoric relations can be observed between cospecifying expressions. A pair of antecedent and anaphor is always cospecifying, while on the other hand, given a set of (more than two) cospecifying expressions, determining the antecedent to a given expression is not necessarily trivial. Anaphors can be further differentiated according to the nature of the lexical items taking part in the relation. Bridging relations, in contrast, occur between non-cospecifying expressions only. Here, the criterion for division into sub-types is the conceptual relation between the entities denoted by the expressions taking part in the relation. Finally, it is possible for an expression to be antecedent to more than one anaphoric and / or bridging expressions at the same time, while we believe that the reverse, i.e. one expression having more than one antecedent, is not possible.</Paragraph>
  </Section>
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