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<Paper uid="J02-1001">
  <Title>Binding Machines</Title>
  <Section position="8" start_page="15" end_page="16" type="evalu">
    <SectionTitle>
5. Example and Discussion
</SectionTitle>
    <Paragraph position="0"> The above unification-based specification of binding constraints, while ensuring their integration into grammar, allows the binding module to be suitably hooked up with systems of reference processing. Feature ANTEC is the interface point between them.</Paragraph>
    <Paragraph position="1"> 14 Clauses II and III constrain LIST-A and LIST-Z, respectively. Roughly, Clause II ensures that the LIST-A value is passed from the lexical head to its successive projections, and also from the head-daughters to their arguments. Note that exemption occurs when principleA(</Paragraph>
    <Paragraph position="3"> is the empty list, in which case the reflexive should find its antecedent outside any binding constraint (Pollard and Sag 1994, Chapter 6).</Paragraph>
    <Paragraph position="4"> Clause III ensures that, at the top node of the grammatical representation, LIST-Z is set up as the LIST-A value of that node, and that LIST-Z is successively incremented at the suitable downstairs nodes by appending its value with the LIST-A value of those nodes.</Paragraph>
    <Paragraph position="5"> At the lexical entry of a predicator, LIST-A is defined as the concatenation of the R-MARK values of its subcategorized arguments specified in the ARG-S value.</Paragraph>
    <Paragraph position="6"> For a detailed specification of the Binding Domains Principle, see Branco (2000). 15 Reference markers can be introduced linguistically, by the utterance of the corresponding expressions, or nonlinguistically, by means of their cognitive availability in the context of the discourse. Theories of natural language semantics can be used to represent these two types of reference markers. Nevertheless, only a global theory encompassing natural language and cognition seems to be able to pursue the ambitious goal of providing an integrated account of how both types of markers, and not only those linguistically evoked, are introduced into semantic representation.</Paragraph>
    <Section position="1" start_page="15" end_page="16" type="sub_section">
      <SectionTitle>
Branco Binding Machines
</SectionTitle>
      <Paragraph position="0"> We are following a distinction between the notions of anaphor resolution and reference processing commonly assumed in the literature. Anaphor resolution is seen as being concerned with the task of identifying the antecedents of anaphors. It is therefore part of a reference-processing system, whose overall goal, in turn, is to determine the interpretation of the anaphors. This involves determining the appropriate semantic type of the anaphoric link between an anaphor and its antecedent (coreference, bridging, e-type, bound anaphora, etc.) and providing a suitable semantic representation for this link.</Paragraph>
      <Paragraph position="1"> Being the interface point between grammatical representation and reference processing, the list value of the feature ANTEC has just to be reduced by anaphor resolvers, given the relevant preferences and filters other than binding constraints, until the most likely antecedent is isolated. It is thus a process concerning selection in a list, rather than search in a set of indexed trees.</Paragraph>
      <Paragraph position="2"> As to reference processing in general, the specification suggested in the previous section provides a suitable framework for the correct representation of the semantically different types of anaphoric links, the range of options not being restricted to coreference only. After the anaphor has been resolved, the reference marker of the anaphor and the reference marker selected as the antecedent can be related in accordance with the mode of anaphora determined by the reference-processing system.</Paragraph>
      <Paragraph position="3"> This semantic relation between anaphorically related reference markers can be represented simply as another DRS condition in the CONDS value. This makes possible a mainstream DRT representation for the resolved anaphoric link, thus building on the substantial number of already worked out solutions available in the literature for DRT-based semantic representation of anaphora.</Paragraph>
      <Paragraph position="4">  This specification of binding theory for HPSG was tested with a computational implementation using ProFIT (Erbach 1995). In this implementation, the relational constraints corresponding to binding principles were straightforwardly encoded by means of Prolog predicates associated to the lexical clauses of anaphoric expressions, and defined in terms of simple auxiliary predicates ensuring the component operations of list appending, list difference, and so on. It is worth noting that some of these predicates have arguments--for example, the LIST-U value, whose value is computed when the whole relevant grammatical representation is built up. This is a consequence of packing nonlocal information in such lists. As in Johnson's approach, it requires that some delaying device be used, which in this computational grammar was done by resorting to the Prolog built-in predicate freeze/2.</Paragraph>
      <Paragraph position="5"> For the sake of the example, consider the following multiclausal sentence from Portuguese displaying backward anaphora between a topicalized reflexive and a pronoun: null (6) De si pr'oprio, cada estudante disse que ele gosta.</Paragraph>
      <Paragraph position="6"> of him self every student said that he likes 'Himself, every student said that he likes.' An abridged version of the grammatical representation produced by the implemented grammar for this sentence is presented in Figure 1, where the feature structures below the tree correspond to partial grammatical representations of the constituents 16 See Kamp and Reyle (1993) for a comprehensive rendering of DRT, and Branco (2000, Chapter 5) for an overview concerning the semantic representation of different modes of anaphora.</Paragraph>
      <Paragraph position="8"> Branco Binding Machines in the leaves of the tree, while the ones above the tree correspond to partial representations of some nonterminal nodes.</Paragraph>
      <Paragraph position="9"> First, consider LIST-Z. In the outer nodes of the matrix clause, due to the effect of the Binding Domains Principle, Clause III, the LIST-Z value is obtained from the value of LIST-A, with which it is token identical, comprising the list with a single element h54i. In the nodes of the embedded clause, the LIST-Z value is the concatenation of that upper LIST-Z value and the LIST-A value h24 , 392i in the embedded clause, from which the list h54 , 24 , 392i is the result. LIST-A values are obtained from the representation of the subcategorization frames of the verbal predicators.</Paragraph>
      <Paragraph position="10"> Next, consider LIST-LU. Reading upward, note that at each higher level in the constituency representation, the list gets longer; by the effect of the Binding Domains Principle, Clause I, the LIST-LU value at a given node gathers the reference markers of the nodes dominated by it. At the discourse top node, LIST-LU includes all the reference markers of the NPs in the example, the listh415 , 24 , 247 , 54 , 392i. The Binding Domains Principle, Clause I, also ensures that this list of all reference markers is passed to the LIST-U value of the top node and that it is then percolated down to all relevant nodes of the grammatical representation.</Paragraph>
      <Paragraph position="11"> Taking a closer look at the NPs, it is easy to check that every phrase contributes to the global anaphoric potential of its linguistic context by passing the tag of its reference marker into its own LIST-LU. In the case of the quantificational NP every student, two tags are passed, corresponding to the REFMARK value, providing for e-type anaphora, and the VAR value, providing for bound anaphora interpretations. And in the case of the ctx node, to illustrate how the nonlinguistic context may be taken into account in the linguistic representation, the reference marker h415i is obtained from the set of semantic conditions that conventionally may capture the nonlinguistic context.</Paragraph>
      <Paragraph position="12"> On the other hand, the context also contributes to establishing the anaphoric potential of each NP. This is ensured by the different clauses of the Binding Domains Principle, which enforce the presence of suitable values of LIST-A, LIST-Z, and LIST-U at the different nodes.</Paragraph>
      <Paragraph position="13"> Finally, token identity is ensured between the ANTEC value and the outcome of the different relational constraints that are lexically associated with each NP and express binding constraints. The value of ANTEC is a list that, at this stage of anaphor resolution, records the grammatically admissible antecedents of the corresponding anaphor only in the light of binding constraints.</Paragraph>
    </Section>
  </Section>
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