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<Paper uid="J87-1002">
  <Title>MODUS BREVIS FORMS (MODUS PONENS): Given Premises Conclusion Normal P ~ Q, P Q Missing Minor P--,- Q Q</Title>
  <Section position="14" start_page="4" end_page="4" type="concl">
    <SectionTitle>
6 USEFULNESS OFTHE THEORY
</SectionTitle>
    <Paragraph position="0"> The computational model for the analysis of arguments, as described in the previous sections, is built on a theory of argument understanding; it, in turn, can be used as the basis for an implementation of an argument understanding system. One suggested real-life application area is a complaint bureau for department stores. Future work could include a full implementation of the mbdel, and fine-tuning the design by selecting a particular application area for arguments.</Paragraph>
    <Paragraph position="1"> Although there is no complete implementation of the model to date, an overview of a possible design is presented here, to indicate how the various components of the model could come together into one integrated &amp;quot;system&amp;quot;. (Note that an initial implementation of the model does exist now, written in Prolog (Smedley 1986).</Paragraph>
    <Paragraph position="2"> But this program merely tests the various reception algorithms described in section 2. The evidence oracle is replaced by a &amp;quot;query the user&amp;quot; facility. Nonetheless, the groundwork is in place for a future implementation that tests the other components of the model).</Paragraph>
    <Paragraph position="3"> In Figure 1, there are three main modules: the Proposition Analyzer, Clue Interpreter, and Evidence Oracle. The Proposition Analyzer takes as input the argument itself and produces a representation of its underlying structure. For each proposition of the argument the Proposition Analyzer attempts to assign it a location in the representation tree, indicating to which other proposition it relates (provides evidence for or receives evidence from). The Proposition Analyzer may call on the Clue Interpreter in the presence of clues, to assist in the interpretation. In addition, once an eligible relative to the current proposition is selected, the decision of whether an evidence relation exists is made by the Evidence Oracle, which is passed the two propositions and responds with a yes or no answer. The Evidence Oracle has available, a knowledge base of shared facts and, if ,possible a model of the speaker. Moreover, if certain beliefs of the speaker can be extracted during the tests for unstated premises, the model of the speaker may even be updated by the Evidence Oracle, to aid in the processing of later propositions.</Paragraph>
    <Paragraph position="4"> In the absence of an implementation, the model can still be defended as a useful prescription of analysis of arguments. This is accomplished in Cohen (1983) by hand simulations of a variety of examples, to demonstrate robustness, and analysis of the complexity of the processing algorithms, to demonstrate efficiency.</Paragraph>
    <Paragraph position="5"> Another argument for the usefulness of the argument analysis model is that the theories developed for the model may be applied to the solution of other language understanding problems. As a result, the study of arguments may be viewed as a worthwhile exercise in the study of language. Some examples of the wider applicability of the model are: * It has been shown that extracting the underlying structure of discourse is useful to study the complexity of  analysis. In the modal, the separation of where and how propositions relate has provided a means of monitoring the number of calls to an inference engine, apart from the more difficult measurement of the process of actually filling in missing inferences. Hopefully, some characterization of structures for language problems other than arguments would be extremely beneficial.</Paragraph>
    <Paragraph position="6"> * It has been shown that certain linguistic constructions serve a function in facilitating the analysis process for the hearer. Developing common interpretation rules for various &amp;quot;linguistic clues&amp;quot; should continue for several language understanding tasks.</Paragraph>
    <Paragraph position="7"> * Some insight has been offered into how communication can proceed despite differing beliefs of speaker and hearer. The ideas outlined for recognizing beliefs simi= lar to one's own, for judging plausible generalizations, should extend to other problems where reasoning beyond one's current beliefs is required.</Paragraph>
    <Paragraph position="8"> In addition, very few researchers seem concerned with truly &amp;quot;low-level&amp;quot; operations, determining not just &amp;quot;what's a good representation for discourse&amp;quot; but also how this representation can be derived, the specification of some algorithm for processing. It is in this domain that we feel our research is making a contribution.</Paragraph>
    <Paragraph position="9"> For future work, we are currently developing a model for discourse analysis in general, based on the principles of this model's design. A hypothesis worth investigating from the existing model is that the resulting representation serves to outline both the linguistic structure of the discourse and the intentional structure (the speaker's intentions behind utterances). The idea is that determining evidence relations in an argumentative discourse may best be described as uncovering the intended uses of utterances (e.g., speaker utters P in order to get hearer to believe Q), hence reflecting the plan of the speaker. But this main function of deriving intentional structure must be performed in conjunction with testing &amp;quot;logical&amp;quot; connections between propositions, and recognizing clues, thus isolating linguistic structure (or grouping into segments). We are interested in specifying a processing model for discourse understanding that operates at the level of individual utterances, in the manner of the argument model, to gain insight into how to derive linguistic and intentional structure simultaneously. This research is of significance to the current work of Grosz and Sidner (1986).</Paragraph>
  </Section>
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