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<Paper uid="C96-1048">
  <Title>Dealing with Cross-Sentential Anaphora Resolution in ALEP</Title>
  <Section position="3" start_page="0" end_page="280" type="metho">
    <SectionTitle>
2 The Text Handling System and
</SectionTitle>
    <Paragraph position="0"> the ~Paragraph unit ~ Everyone who writes a grammar within the ALEP platform has some 'contact' with its Text Handhng (TIt) system, which converts each input into a SGML tagged expression. The TH component is the first processing step provided for by the ALEP system. In this tool, the sentence is defined as  tile default linguistic unit. If larger units are to be processed, this has to be explicitely defined by the user. lit our case, the linguistic unit is defined to be 'P' (for 'Paragraph') 2. The output of the TH being for example:  one can refer to the tag 'P' in order to define this structure being the linguistic unit to be processed. As usual (and also obligatory) for tile development of grammars within ALEP, a so-called ts_ls_rule (a mapping between text structures and linguistic structures) has to be defined:</Paragraph>
    <Paragraph position="2"> where a linguistic description ('ld') defining the 'constr(uction)' type of a 'paragraph' is associ~ ated with the tag 'P', symbolizing the text type 'paragraph'. The distinguishing value here is 'paragraph', which has been added to the type .system as a possible value for the feature 'constr': the ALEP formalism being type based, every feature, with its range of possible values, has to be declared in the declaration component.</Paragraph>
    <Paragraph position="3"> The next step involves in the description of gran&gt; mar rules whict, parse tile structure of a paragraph. The phrase-structure rule responsible for the building of the paragraph-structure is simple.</Paragraph>
    <Paragraph position="4"> The mother node simply allows a binary branching of two sentential daughters. A recnrsion is defined on the right daughter, the value of 'constr' being a disjunction of 'punct_att' (describing a sentence terminated by a fall stop) and 'paragraph' (describing thus the recursion). 'l'he left daughter is considered to be the head (structure-sharing of 'head' features), as one can see in the following (simplified) presentation of the rule:</Paragraph>
    <Paragraph position="6"> ~I would like to thank Gordon Cruickshank ((\]ray Systems, Laxembourg) who gave me the initial idea to use this strategy in order to describe the interdependency of information between sentences.</Paragraph>
    <Paragraph position="8"> where '&lt;' symbolizes the immediate dominance relation between the mother and the list of daughters.</Paragraph>
    <Paragraph position="9"> In principle , these are the steps which are necessary in order to extend the coverage of the grammar to larger linguistic units* There is naturally some more technical work to be done, but this will be described in the third chapter, where i will go into more details of the architecture of the grammar development. At this stage, we are able to parse a paragraph and to get a syntactical analyse of this structure. Sonic aspects which are specific to text linguistic should be considered. The one I am concentrating on is the cross-sententiM anaphoric relation. This has been postponed to the semantic which is treated within the re.finemenl component of the grammar. But before explaining the motiwLtion of the grammar design on this point and the reasons for postponing the semantic untill tile process of refinement, the semantic framework which has been choosen for the modelling of the cross-seutential anaphora should be presented*</Paragraph>
  </Section>
  <Section position="4" start_page="280" end_page="282" type="metho">
    <SectionTitle>
3 DPL as Representation Language
</SectionTitle>
    <Paragraph position="0"> for Information-Passing The Dynamic Predicate Logic (DPL) results from an investigation of a dynamic semantic interpretation of the language of first order predicate logic and is &amp;quot;intended as a first step toward a compositional, non-representational theory of discourse semantics ''3. This approach is concerned among other things with the cross-sentential anaphora.</Paragraph>
    <Paragraph position="1"> The dynamic aspect resides in the fact that, for this approach, the meaning of a sentence doesn't lie in its truth conditions, but &amp;quot;rather in the way it changes the ... information of the interpreter ''a.</Paragraph>
    <Paragraph position="2"> DPL considers only the information change which concerns %heir potential to 'pass-on' possible antecedents for subsequent anaphors&amp;quot;5. The Dynamic aI ant refering here to (Groenendijk91).</Paragraph>
    <Paragraph position="3"> 'J Ibid. p. 43 &amp;quot;~Ibid. p. 44  Predicate Logic is based on the syntax of the standard predicate logic, but proposes a new (dynamic) interpretation of the quantifiers and connectives which allows the binding of variables within and outside their scope, depending on the interpretation of the corresponding expressions of the natural language.</Paragraph>
    <Paragraph position="4"> Two (strong) assumptions, which are controversial in the discussion on this topic, are underlying the DPL approach: Indefinite NPs are considered to be quantifiea~ional expressions and pronouns to act like variables. Not everyone agrees on those assumptions, as this can be seen in the Discourse Representation Theory or in the work by Irene Helm 6. But those assumptions are here important if one wants to provide an uniform translation of indefinite NPs into existential quantifier (see below). And the desired compositional treatments requires that the information concerning the pronouns is to be found in the sentences uttered so far, i.e. as included within the scope of a logical quantifier or connective.</Paragraph>
    <Paragraph position="5"> The particular expressions of the natural language  DPL is dealing with are the following: (1) A man walks in the park. He whistles. - cross-sentential anaphora (2) If a farmer owns a donkey, he beats it. - donkey sentence (3) Every farmer who owns a donkey, beats it. donkey sentence And the problem consists in providing an adequate semantic representation of the anaphoric links. There are several ways of representing the semantic interpretation of each of the utterances and three of them (1 - 3) are discussed by Groenendijk &amp; Stokhof: (A) In classical predicate logic:</Paragraph>
    <Paragraph position="7"> indefinite NPs into the representational language, once as an existential quantifier (A,1) and once as an universal quantifier (A,2 &amp; A,3). The fact that (2) and (3) translate into the same semantic representation is also reflecting the non-compositionality of the classical predicate logic in this case.</Paragraph>
    <Paragraph position="8"> The problems with the compositional representation (B) are concerning the binding of the variables (the pronouns in the natural language). In (B,1) the third occurence of the variable x is free and thus doesn't allow the anaphoric reading. The same remarks are valid for x and y in (B,2) and for y in (B,3). But the way (S) is representating the utterances allows the uniform translation of indefinite NPs into an existential quantifier.</Paragraph>
    <Paragraph position="9"> The problems with the DRT representation are more of methodological nature, since on the treatment of those cases, DPL and DRT are empirically equivalent. In short: Groenendijk and Stokhof are missing the compositional building of the semantic representation and also would prefer to use a more classical representational language, like the one of first order logic. For this, they are 'merging' together the representation (A) and (B), and considering now only the first case (1), the dynamic semantic interpretation is going to be like (B,1): ~z\[man(x) A walk_in_the_park(x)\] A whistle(x), but with the existential quantifier having scope over the conjunction of the two sentences, this representation is going to be equivalent to:</Paragraph>
    <Paragraph position="11"> This is possible because the interpretation of a sentence doesn't lie in a set of assignments, but rather in a set of ordered pairs of assignments, where those pairs represent the input-output states of a sentence.</Paragraph>
    <Paragraph position="12"> In our example, the first sentence has an output which is as the same time the input of the second one. Since the existential quantifier is interpreted as being able to quantify outside its scope (also in combination with the conjunction and the sequencing of sentences), the information concerning the (possible) antecedent is going to be passed-on to following sentences, which could be subsequently uttered. The fact that the existential quantifier in DPL is interpreted as a quantifier which can bind outside of its syntactic scope allows to say that we provide a compositional treatment of the utterance, the second sentence being interpreted as it comes, without referring to some metalinguistical representation or process. The existential quantifier is qualified as an externally dynamic quantifier.</Paragraph>
    <Paragraph position="13"> Not every quantifier (or connective) has the dynamic property of binding outside of its scope; the universal quantifier, for example, can bind within  its scope, but not outside of it: (4) *Every man walks in the park. He whistles  is ruled out. The dynamic semantic interpretation of this quantifier blocks the passing of the information: the ouptut of the first sentence is empty (with respect to the information concerning anaphoric binding). The input of the following sentence will therefore contain no information allowing a resolution of the pronoun.</Paragraph>
    <Paragraph position="14"> The way DPL is interpretating the distinct quantitiers and connectives is the following one:  This is too simple and for sonre English examples it seems to be wrong. The authors arc considering and discussing the cases which contradict the assumptions and give some hints in order to integrate those cases. I will not discuss this point here, but just mention, that for the German grammar we should have a look at a detailled analysis of the meaning of such expressions 7. Once this has been done, we can encode this information in the lexicon (as will be seen in the next section). But here we can say that the DPL approach allows us, to a certain degree, to account for the resolution of anaphora without having to leave the field of linguistic descriptions. With the only means of the grammar and the formalism we have, we are able to provide a tirst and simple description of those phenomena. It is still to be investigated how sophisticated such a treatment can be.</Paragraph>
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