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<Paper uid="C90-3073">
  <Title>Knowledge Representation and Semantics in a Complex Domain: The UNIX Natural Language Help System GOETHE</Title>
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OLIVETTI D.O.R. - TA RESEARCH LAB
TA TRIUMPH-ADLER AG
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  <Section position="2" start_page="0" end_page="0" type="metho">
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8500 Nuremberg (West Germany)
1 Abstract
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    <Paragraph position="0"> Natural language help systems for complex domains requirc, in our view, an integration of semantic representation and knowledge base in order to adequately and efficiently deal with cognitively misconceived user in-.</Paragraph>
    <Paragraph position="1"> put. We present such an integration by way of the notiml of a frame-semae~tics that has been implemented for the purposes of a natural language help system for UNIX.</Paragraph>
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  <Section position="3" start_page="0" end_page="361" type="metho">
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2 Introduction
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    <Paragraph position="0"> It is commonly agreed ihat natural language systems fox&amp;quot; semantically rich domains require a level of sema~tic representation in order to provide for a sufficiently deep processing of the natural language input.</Paragraph>
    <Paragraph position="1"> The level of semantic representation is sometimes called a representation of linguistic knowledge. In addition, a natural language help system also requires a lo~owledge base of the application domain in order to answer the requests for domain specific help. The level of knowledge representation is sometimes called a representation of world knowledge. Most present day natural language processing sy,'stems, including, amongst others, SRI's Core I_,anguage Engine (Alshawi et.al. 1986), ESPRIT I project ACORD (Bez et.al. 1990), and the UNIX natural language help systems UNIX-Consultant (Wilensky et.al. 1988), SINIX-Consultant (Wahlster et.al. 1988), and AQUA (Ouilici et.al. 1986), keep the two levels of representation distinct. In addition, there usually is no feed-back of information between the semantic representation and the knowledge base. Thus, parsing is supposed to result in a complete semantic representation of the user input which then is passed on to tilt knowledge base manager for further processing. This kind of architecture follows a strategy, that can be called stepwise processing. We claim that for complex domains this kind of approach is inadequate because it ig,mrcs the user's cognitive misconceptions about the particular application. Instead, we wish to argue that at least with respect to semantics and knowledge representation in natural language help systems an h~tegmted approach should be preferred, in the approach we advocate, semantics and knowledge representation interact to correct (or complete) a possibly incorrect (or incomplete) semantic representation. The mechanism by which this is achieved is based on the notion of a fi'ame-semandcs (cf. Heyer et.al. 1988, tlausser 1989). We demonstrate our &amp;quot;integrated approach with examples from GOETHE, a natural language help system for UNIX as a complex domain.</Paragraph>
    <Paragraph position="2"> GOETHE (cf. Kese/ Oemig 1.989) has been developed together with OLIVETTI AI Center, Ivrea, and Tecsicl AI Lab, Rome, for UNIX V on the OLIVETTI LSX 30xxComputer Series. The present prototype includes a protocol for monitoring user's actions and has the natural language mode of interaction fully integrated into a graphical DeskTop under InterViews (based oll a cooperation with Fraunhofer Society, Stuttgart), thus allowing also for deictic natural language and graphical interactions.</Paragraph>
    <Paragraph position="3"> It covers all of UNIX' file handling, containing a static knowledge base of more than 70 UNIX programs. It is written in Quintus-PROLOG and C, and takes by average less than 10 seconds for generating an answer to a user's request.</Paragraph>
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  <Section position="4" start_page="361" end_page="361" type="metho">
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3 Requirements on Knowledge Re-
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    <Paragraph position="0"> presentation and Semantics for a UNiX natural language help system It is the task of the knowledge base in a UNIX natural language help system to serve as a baals for correctly and adequately answering a user's questions in one of the following situations: (1) the user needs to know a UNIX cormnand, or series of commands in order to carry out a certain i:ask, (2) hc has sent off a I JNIX command and the system has resulted in a different .qa\[e !ban he expected, or (3) he wants to gc.t irffcrmalion about a UNIX command. In g,.mcr~fl, !hi:; ',,,'ill require two knowledge ~,:)urces: 5'laEc knowledge about UNIX as a co\]!c;ction of possible, man-machine interactions, and dynamic knowledge about the respc'cl.i-,e UNIX st:ate (in particular, inode~ a~d the associated files with their permissions), the u.-,~:t ...... s actions, and the i'&amp;quot;' ...... &amp;quot; r~:actions (in particular, error ': ~ l.,~ ill ,~ messages), it is the task of the semantic representation to provide ,t .. ,,'~c knowledge base manager wi:\[t a corrc.ct and adequate semantic representation of \[he user's input Si\[ ll\[ff\[ Ion) (in -~ spccii!ic : ' ' There basically are two stratC/oies..:, . available at this point. ()q ~.he (:re na~.:d, adhering to the idea that c~-occur~en:e ...,,~, ,..ns va,so for missing :. c u-,.:t,g q ,.:.cc2d to be treated as real res!ric{io~u,, p., ;:-ibly even as syntactic :c.&lt;tric:ions (('homsky !965), we can insist that ;:' there is a semantic representation ~&gt;f an input sentence at all, it will be COITCCl zl~cl c'ot?,\])IU.e ~-:' O.,.~ respect to the domain e,f .q)p!ication). He.nee, the system will &amp;quot; ' tat! ~X) provide ~\[I1 ;&amp;nswer to a user's \[tilde z,. he rCqtlCSt ~ t .... D~rases his question in a correct and comp!ctc way. On the other hand, co-occurrence restrictions may not be ~ak6'n as; real restrictions but rather as scnzezmic d@z,/ts which may be overwritten by additional knowledge base itfformatic.,n. Fhis allows for a much more use&gt;friendly and cooperative natural language processing, but requires that the se:n}antic re'presentation is closely tied to )- 'd'.e know edge base.</Paragraph>
    <Paragraph position="1"> For the purpost:s el! the GOETHE system, we have opted for the second alternative, because the cognitive misconceptions a user may have about UNIX not only cause him to invoke the help system, but also cause him in most cases to phrase his questions ~1 the way he does: If the system is presented with a semantically incorrect question, this is to be taken as an indication, that the user needs help, and a reminder that he better rephrase his question in a correct way will not be of much use to him. Of course, it would have also been possible to relax tile syntactic co-occurrence restrictions. In effect, however, this would have resulted in a duplication of knowledge base information in the lexicon. The second alternative, therefore, not only appears to be the more adequate, but also the more efficient solution.</Paragraph>
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