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<Paper uid="C82-1031">
  <Title>The Anatomy of a Systemic Choice</Title>
  <Section position="4" start_page="195" end_page="195" type="metho">
    <SectionTitle>
4 Asking, Answering and Choosing
</SectionTitle>
    <Paragraph position="0"> The Nigel grammar which this paper represents contains over 200 systems, each raising relatively specific issues 3. There are some strong patterns in the sets of questions which Nigel's choice experts address to its environment. Three kinds of questions are particularly influential in determining what is  generated: 1. Some questions are used to determine whether information of a certain character is available, such as the location or duration of an event. These are generally used just before other questions that seek to characterize information.</Paragraph>
    <Paragraph position="1"> 2. Some questions try to categorize or characterize available information. These questions  used for information characterization are the most numerous. They are used to subcategorize, and also to discover relations of inclusion, identity, precedence, adjacency, and attributes of manner, number, completeness, intended emphasis, identifiability to the reader, decomposability, gender, hypotheticality, extensionality, and many other sorts. 3. Several questions about preference are concerned with whether available information should be expressed.</Paragraph>
    <Paragraph position="2"> Note that for each of these kinds of questions, the set of possible answers is olosed, since it is fixed by the inquiry and predictable in advance.</Paragraph>
    <Paragraph position="3"> 198 W.C. MANN Because in this model there is a definite boundary betw~ en the grammar and its environment, and knowledge of the world and the intended communication belong to the environment, we could put a particular grammar in very different environments, and as long as the questions received the same answers, the generated units would be the same. This leads to two basic observations about answering:  1. The method which the environment uses to determine its answer is not part of the grammar. A description of the grammar can therefore omit these methods.</Paragraph>
    <Paragraph position="4"> 2. The range of possible answers must not vary from one environment to another; rather it must  be controlled (definitionally) by the grammar, and so a description of the grammar must include them.</Paragraph>
    <Paragraph position="5"> Since the answers given to each choice expert have a predictable range, the response of the choice expert can be completely determined in advance. For each of the possible answers, there is a next action, either a question to ask or a choice to make.</Paragraph>
    <Paragraph position="6"> The questions, answers and choices therefore form a Decision Tree.</Paragraph>
  </Section>
  <Section position="5" start_page="195" end_page="195" type="metho">
    <SectionTitle>
5 The Incompletness of Asking, Answering And Choosing
</SectionTitle>
    <Paragraph position="0"> The account of choice experts above is defective in that it does not adequately identify the subject matter of the choice expert's questions. 4 The environment is not required to remember anything about the ongoing &amp;quot;conversation&amp;quot; with the grammar, so the grammar must provide all continuity by identifying, remembering and asking about items in its environment.</Paragraph>
    <Paragraph position="1"> We call an item in the environment a hub, by analogy to the hub of a spoked wheel, partly because in a network representation of knowledge such items tend to have a well-identified central structure with connections to surrounding structures.</Paragraph>
    <Paragraph position="2"> The grammar's memory of entities in the environment is creted by  1. Getting the environment to supply symbols to represent its entities.</Paragraph>
    <Paragraph position="3"> 2. Associating these symbols with grammatical funciton symbols, 3. Writing questions (in choice experts) in terms of these grammatical function symbols, 4. Translating questions (at presentation time) to include hubs instead of the associated  grammatical function symbols, using a process called the Mediator.) The first step, getting the environment to supply symbols, requires that the choice experts employ a second class of questions. They differ from the ones presented above in that the allowable answers are drawn from open sets, and the questions do not correspond to branch points in the decision trees of the choice experts.</Paragraph>
    <Paragraph position="4"> The interface between grammar and environment is a two-layer boundary, with the Mediator process between the boundaries performing the inquiry translations. It is a simple substitution process that uses a table of the existing associations between grammatical functions and hubs. The environment's responses are not translated.</Paragraph>
    <Paragraph position="5"> The mediator isolates the grammar from the symbol system of the environment. The ~;ammar is written in terms of grammatical functions; no symbols from the environment are written into the g, arnmar. Conversely, the environment does not encounter grammatical function symbols in questions. It sees only the question symbols of quastion3 and hub names it has itself supplied.</Paragraph>
    <Paragraph position="6"> THE ANATOMY OF A SYSTEMIC CHOICE 199 The most important consequence of this arrangement is that the grammar can operate without any particular sensitivity to how knowledge is represented in the environment.</Paragraph>
  </Section>
  <Section position="6" start_page="195" end_page="195" type="metho">
    <SectionTitle>
6 Creating Function Associations
</SectionTitle>
    <Paragraph position="0"> Associations between grammatical function symbols and hubs provide the continuity in the grammar's interaction with its environment. These associations are an extension of the notion of a function symbol, since we can now ask of a function symbol what concept it represents and also what linguistic realization it has.</Paragraph>
    <Paragraph position="1"> This extension seems particularly natural where reference is being performed. Function symbols such as ACTOR and BENEFICIARY are already in the grammar, and in satisfying intentions to communicate, ACTOR will be associated with hubs for actors, BENEFICIARY with hubs for beneficiaries, and so forth.</Paragraph>
    <Paragraph position="2"> This use of function symbols is an extension in another way. Some function symbols will be associated with hubs but will not correspond to constituents in the generated structure. In Nigel the function symbols EVENTTIME and RELEVANTTIME are used in the reasoning about tense, but do not have their own distinct constituents in clauses. The function symbols SPEAKER and HEARER are used in reasoning about pronouns, and the symbol SPEECHACT is used in reasoning about mood.</Paragraph>
    <Paragraph position="3"> These various uses of function symbols are compatible: the way of identifying the hub to be associated with a function does not depend on whether that function will be inserted into the structure. Several functions are inserted in some instances but not others, and yet they carry the same hub information in each case. (For example, AGENT would carry the same hub symbol for either &amp;quot;Someone closed the door&amp;quot; or &amp;quot;The door was closed,&amp;quot; but it would be inserted only in the second case.) Associations between function symbols and hubs are created by the method used to present an open.set question to the environment. Part of the specification of such a question is the function symbol with which the environment's response will be associated. That symbol must not have an existing association when the question is asked. Associations therefore cannot be changed, once made.</Paragraph>
  </Section>
  <Section position="7" start_page="195" end_page="195" type="metho">
    <SectionTitle>
7 Conclusions
</SectionTitle>
    <Paragraph position="0"> We have presented a new way of thinking about choices, representing them, identifying their content, and progressively making the notion of grammatical choice more explicit. The key conceptual elements are the distinctness of the grammar and its environment, the metaphor of a choice expert who asks questions, closed sets of question and answer symbols, open sets of hubs and hub identifiers, association of hubs with grammatical function symbols and choice expert processes as decision trees.</Paragraph>
    <Paragraph position="1"> This conception is compatible with the systemic framework and contributes to it. At the same time, it simplifies talking about how systemic grammars fit with various concepts of text and communication, and since it helps relate text to intentions to communicate, it contributes directly to the art of computer text generation.</Paragraph>
  </Section>
  <Section position="8" start_page="195" end_page="195" type="metho">
    <SectionTitle>
200 W.C. MANN
Footnotes
</SectionTitle>
    <Paragraph position="0"> these ideas to the interaction with the lexicon is outside the scope of this paper. However, see \[Matthiessen 81\] for a description of how the lexicon, grammar, and knowledge representation of the environment might be suitably related.</Paragraph>
  </Section>
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