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<Paper uid="J99-2001">
  <Title>A Methodology for Extending Focusing Frameworks</Title>
  <Section position="8" start_page="190" end_page="191" type="concl">
    <SectionTitle>
8. Conclusions
</SectionTitle>
    <Paragraph position="0"> The notion of local focusing and its influence on pronoun resolution has been found useful in many aspects of NLP. However, previous work on local focusing has ignored complex sentences even though they are prevalent in naturally occurring text. The problem that we faced was one of determining a reasonable way to extend a focusing algorithm to handle these sentences. Previous methodology (i.e., using semantically neutral text) was too simplistic and nearly impossible to utilize. A solely corpus-based analysis was impossible because of the variety of a priori decisions that needed to be 18 We thank Susan Brennan for first raising the question of how then affected the judgments in this experiment. We note that Walker (1993) explored the role of now in centering.</Paragraph>
    <Paragraph position="1">  Computational Linguistics Volume 25, Number 2 made and because of the complexity of interaction among factors in naturally occurring discourses. This work presents a methodology that calls for the systematic construction of texts. It relies on the potential tension of semantic factors with focusing factors to identify possible extensions of a focusing framework to account for a particular kind of complex sentence. The methodology has been used to extend a focusing framework (RAFT/RAPR) to handle one type of complex sentence (&amp;quot;SX because SY&amp;quot; sentences). We illustrated the SSD Methodology by 1) explaining how the first part of the methodology led to the Prefer-SX hypothesis (a hypothesis about how readers prefer to resolve subjects in a sentence following an &amp;quot;SX because SY&amp;quot; sentence); and 2) discussing a (scaled-down) preliminary corpus analysis we performed to test the validity of the Prefer-SX hypothesis. We relaxed the methodology for the purposes of the preliminary corpus analysis because of the enormous amount of work required to perform the corpus analysis properly and because we felt that the corpus analysis would reveal more issues to be addressed prior to a proper corpus analysis. As reported in this paper, the corpus analysis did not refute our Prefer-SX hypothesis, and it did indeed reveal more issues that need to be addressed in this type, or any other type, of corpus analysis to examine focusing methodologies.</Paragraph>
    <Paragraph position="2"> Note that one very important point raised by the preliminary corpus analysis is that the numbers derived during a corpus analysis are prone to represent not just the influence of the focusing framework, but the influence of world knowledge, semantics, and other pragmatic factors. Therefore, corpus analyses must be considered with this in mind. Because the problems that arose during our preliminary corpus analysis will arise during any kind of corpus analysis, we believe that our SSD Methodology is important for deciding how to extend a given focusing framework, and for comparing two focusing frameworks.</Paragraph>
    <Paragraph position="3"> In fact, we feel that a corpus analysis to verify findings based on the SSD Methodology should be withheld until the processing of many kinds of complex sentences using the SSD Methodology has been analyzed. It would be better still to have an inference tool with which to reject referents based on semantics, world knowledge, pragmatics, etc. This would allow us to apply focusing algorithms to a corpus and automate the comparison of focusing algorithms, by adding functions to track and compute the frequency information (like the frequency information shown in Tables 2 to 4) that is needed for a corpus analysis.</Paragraph>
    <Paragraph position="4"> The reader should note that the preferences for pronoun resolution that we identiffed (i.e., the Prefer-SX Hypothesis) refute an assumption sometimes made by researchers regarding complex sentences: that the clauses of complex sentences can be processed in a strictly linear order. Our findings indicate that the appropriate contents of the focusing data structures after processing $2 should be much more heavily influenced by the SX clause (and not by the SY clause, as the previous assumption would require). We stress that these findings are relevant for other focusing frameworks, not just RAFT/RAPR, and they indicate the importance of studying complex sentences.</Paragraph>
    <Paragraph position="5"> Furthermore, as explained in detail in Suri (1993), the SSD Methodology can also be used to compare local focusing frameworks. Thus, this methodology allows the study of focusing phenomena and algorithms related to focusing phenomena.</Paragraph>
  </Section>
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