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<Paper uid="P85-1029">
  <Title>DESCRIPTION STR.ATEGIE.S FOR NAIVE AND EXPERT USERS</Title>
  <Section position="4" start_page="0" end_page="238" type="metho">
    <SectionTitle>
OUR DOMAIN
</SectionTitle>
    <Paragraph position="0"> Our goal is to characterize some of the strategies employed to describe complex physical objects and see whether these strategles are different for naive and experts users. To investigate thus problem, we have looked at texts from encyclopedias {botih adult and junior) and high school physics textbooks ~. The texts we have studied are about physlc~l objects performing a function (such as telephoues and telescopes), and generally do not exceed several paragraphs in length.</Paragraph>
    <Paragraph position="1"> These texts make the distinction between na4ve and expert readers ~nd have been widely used for a number of years for those audiences. They provide examples of different descriptive strategies that actually occur in natural language. Thus, a question-answering system should be able to reproduce them-'.</Paragraph>
    <Paragraph position="2"> Studying texts from encyclopedias gives us the advantage of being able to compare descriptions of identical objects aimed at two distinct audiences. On the average, a younger audience has had less opportunity to gather experience and knowledge about any. particular doma4n. Thus a younger audience as a -whole is more naive about ~ domain than an adult audience. Hence, these texts give us a good starting point for studying the differences between the IWe studied about fifteen examples from each encyclopedia and textbook. 2Our goal however, is not to study, how effective these tex~s ~re for different human rea(iers. If further psychologlcal research shows that other distinctions ~.re * ppropriate, they could be . incorpoTated.. . The dustinction based on encyclppedias and textbooks is * really the only available at thls point.  1) The hand-sets introduced in 1947 consist of a receiver and A transmitter in a single housing available in ,black or colored plustic.</Paragraph>
    <Paragraph position="3"> 2) The transmitter diaphragm is clamped rigidly at its edges 3) to improve the high frequency response. 4) The diaphragm is coupled to a doubly resonant system 5) -s cavity and an air chamber- 0) which broadens the response. 7) The carbon chamber contains carbon granules, 8) the contact resistance of which is varied by the diaphragm's vibration.</Paragraph>
    <Paragraph position="4"> g) The receiver includes a ring-shaped magnet system around a coil and a ring shaped armature of anadium Permendur. 10) Current in the coil makes the armature vibrate in the air gap. 11) An attached phenolic-impregnated fabric diaphragm, shaped like a dome, 12) vibrates and sets the air in the canal of the ear in motion.</Paragraph>
    <Paragraph position="5"> I. Constituency Depth.attributive for the tronamitt~ Depth-attributive far the receiver (Description of the trQnamitt~) (Description o\[ the receiver) 2. Depth-Attributive 9. Depth-Attributive 3. Cause-effect 10. Cause-effect 4. Depth-Attributive 11. Attributive 5. Depth-identiflcation 12. Ca-,e-effect 8. Cause-effect 7. Depth-Attributive 8. Cause-effect</Paragraph>
    <Section position="1" start_page="238" end_page="238" type="sub_section">
      <SectionTitle>
F|gure is Constituency Schema Example
</SectionTitle>
      <Paragraph position="0"> aescnpttons given to naive users and those glven to experts in the domain. To minimize the effects of styiistlc differences on our results, we chose texts from several different encyclopedias in each audience category.</Paragraph>
    </Section>
  </Section>
  <Section position="5" start_page="238" end_page="240" type="metho">
    <SectionTitle>
THE TEXTUAL ANALYSIS
</SectionTitle>
    <Paragraph position="0"> We began by analyzing the different texts using methods developed by other researchers ( \[Hobbs 78a), \[Hobbs 80l, \[Mann 84\], \[McKeown 82\]) we decomposed paragraphs in terms of their pmmitwe rhetorical structure ia an attempt to find a consistent structure tn each group of texts. The analy.~s showed the adult encyclopedia descriptions to be mainly m terms of the sub-parts of the object being descrlbed These texts can be characterized by one of the textual structures posited tn \[McKe0wn 82\], the constituency schema. This structure is presented m the next section. On the other hand, no schema or other organizing structure consistently accounted for the descrlptmns m the junior encyclopedia texts In looking for other types of organizing srrategles, we discovered that the ma~n strategy m descrlbmg cblects to a naive user is to trace through the process that allows the obiect to perform Lts function.</Paragraph>
    <Paragraph position="1"> Strategy for the Adults The descriptions from the adult encyclopedias tend to follow the pattern estabhshed by the constltuency schema, one of the textual structures defined m \[McKeown 82\[. In her work on natural language generation, McKeown studied the problems of what to say and how to organize text coherently. She examined texts and transcripts, classifying _ each sentence as one of a set of rhetorical predicates 3 and found that some comblnatmns of predicates were more likely, to occur than others. Moreover. for each discourse sltuation, some combination would be the most appropriate one. Those standard combinations were encoded as schemas which axe associated wlth a particular dLscourse situation. One of these schemas is the constltuency schema which is used to descrlbe an object (or concept) m terms of its subparts and their properties. The constituency schema is shown below ~ (For a given entity, Constituency LS the description of its sub-parts or sub-types, and the attributive predicate glees properties associated with it.) 3Rhetorical predicates characterlze the structural purpose of a sentence and have been discussed b~&amp;quot; a vamety of linguists \[Grimes 75\] fHobbs 78b |S6me examples are constituency (describtlon of sub-parts or sub-types), attributive (providing detad about an entity or event) and analafy (-the making of an analogy). 4We have altered McKeown's constituency schema slightly by making the first predicate optionkl Instead. of mandatory: in the texts studied, the main parts o{ the object were not necessarily immediately lis~ed. We ,~,e using McKeown's notation:&amp;quot; {}&amp;quot; mdicatd optlonality, 'p indicates alternatives, &amp;quot;/&amp;quot; indicates that the item may appear 1-n times, and &amp;quot;*~ indicates that the item may appear 0-n times. Finally, &amp;quot;;&amp;quot; is used to represent clszsificatlon of ambiguous propositions.</Paragraph>
    <Paragraph position="2">  =_ L l)W~en one speaks Into the transmitter of a modetqt telephone, these sound waves strike a~galnst an aluminium diak or diaphra~n and eause it to vibrate back and forth In Just the ~me way the molecules of air m~ vibrating.</Paragraph>
    <Paragraph position="3"> IT. 2) The center o/ thin diaphra~nn ia connected with the carbon button originally invented b~ Thomas A. Edieon. 3) Thi~ ie a little buns, bo: filled with granules o/carbon composed of eapeciall;; ~dccted and treated coM. 4) The front end back of the button are inaulntcd. Ill. 5) The talking eu~ent Is paNed through this box so that the eleetrlelty must find Its way from gs~nule to g~qmule luside the box. 6) When the diaphragm moves Inwm~l under the pressure f~om the sound waves the e~bon g~dn~ are pushed together and the eleetrlelty finds an ea~le~ path. ~) Thus s strong eurtent flows through the line. 8) When a thin im~t|on of the sound wave comes along, the diaphragm sprln~ back, allowing the e~bon pm'tleles to be mote loosely packed, and eonsequently less eu~.ent can find Its way through. g) So s varying or undulating current Is sen~ ove~ the line whuse vibrations exactly eorr~pond to the vibrations caused by the speaker's volee. 10) ThIs euetent then flows through the line to the colic of an elcctromafnet in the receieer.</Paragraph>
    <Paragraph position="4"> IV. 11) Ve~ near to the pa/u of thie magnet i, a thin iron di~e V 12) When the eurtent becomes stt, onge~ it pulls the disc toward it. 13) As s weaker eur~ent flows through the resigner, It Is not strong enough to att~set the dlsk sad It springs back. 14) Thus the dlaphrs~m In the receiver Is made to vibrate In and out ....  Consider for example the descnptlon of a telephone from an, adult encyclopedia \[Colher 62\] shown in Fzgure 1 ~. In the first sentence, the telephone is described In terms of its constltuency (or sub-p~xts}: the transmitter, the receiver and the housing From s~ntence 2 to 8, attributive reformation (or properties) ~s well as functlonM Info~matlon (causeeffect) about the transmltter axe glven ~ Finally, the recelver ~n turn ~s described from sentence 9 to 12, uslng both attributive and c~use-efrect information.</Paragraph>
    <Paragraph position="5"> SFor clarity, the original one paragraph text has been divided mto three paragraphs. SThe reader who is familiar with this type of ~nalysm will note that several properties bf the transmitter are in turn identified and described uslng attributive reformation which is a form of schema regnrs|on, Entries in the junior encyelopedla ~nd hlgh school text books In texts aimed toward younger audiences, an object is m~nly described in terms of the functions of its parts. The description traces through the process reformation instead of an enumeration of its sub-parts, * s is usuMly the case in the adult descriptions. The p~rts are mentloned only when they&amp;quot; need to be, that is, when the descnption of the mechanical process calls for them. As an example of this phenomenon, consider the description of a telephone show.n tn Figure 2, taken thls tIJne from the encyclopedia lunior \[Bntanmc~-Junior 6,3\]' : We see that the theme of this text is the mechanlcM process description shown in bold face.</Paragraph>
    <Paragraph position="6"> That process descnptlon gets interrupted when descnptlve informatlon can be included concerning sub-paxt that was just mentioned as part of the process descnption. Such information Is shown zn indented it~lics in the example.</Paragraph>
    <Paragraph position="7"> Furthermore, we see that, in the junior encyclopedla, not only ts the description made mainly through a process trace, but there are no large gaps in  ; Description of the TELEFHOKE btaed on the Constituency uchens. .u~wY axe the unique identifiers fur the object frtae8.</Paragraph>
    <Paragraph position="8">  the chain of references Almost everyttung is spelled out. Consader the third paragraph of the text glven ~bove where every step s explained: &amp;quot;The talking current is passed through this box SO THAT the electricity must find its way</Paragraph>
  </Section>
  <Section position="6" start_page="240" end_page="240" type="metho">
    <SectionTitle>
FROM GRANULE TO GRANULE inslde the box.&amp;quot;
</SectionTitle>
    <Paragraph position="0"> From there, the writer goes on to explaan how the electricity passes through the carbon box, once again stepping through the process, spelhng out the consequences of e~ch step: &amp;quot;When the diaphragm moves inward under the pressure f~m the sound waves the carbon grains are pushed together and the electricity finds an easier path. THUS a strong current flows through the line.&amp;quot; Contrast this detmled procpcr~s descnptmn with the descriptmn given for an adult&amp;quot;: &amp;quot;The carbon chamber contains carbon granules, the contact resistance of which is varied by the dlaphragm's v|bration'.</Paragraph>
    <Paragraph position="1"> Other differences occurred between the jumor and adult entries as well. In general, more vlsual tnformatlon was included m the text for the junior, so as to render the description more vlvld. For exampl e, the carbon button in the telephone descnptlon Is described as &amp;quot;a !ittle brass box filled wlth carbon of especlally selected and treated coal&amp;quot; m the junior 8This excerpt is taken from an adult encyclopedia. encyclopedia, in contrast to &amp;quot;the carbon chamber contains granules&amp;quot; m the adult encyclopedia, similarly, the junior entry for light bulbs describes a filament as a &amp;quot;fine run.ten filament wound m very small coils&amp;quot;, whereas the adult encyclopedi~ mentlons only &amp;quot;~ coded tungsten filament.&amp;quot; Another malor difference was that the lumor encyciopedi~ texts had a higher degree of redundancy while the adult encyclopedia ones were quite concise We refer to the jumor telephone example again to illustrate this point: sentences $ and 6 explained how the electnclty Is made to flow easily through the box Sentence 7 xs a recapttulatlon of that phenomenon.</Paragraph>
    <Paragraph position="2"> Finally, sentence 8 explains the reverse effect Finally, we observed that expository style and vocabulary differed considerably m the two types of texts studied. Future research will attempt to characterize these phenomena.</Paragraph>
  </Section>
  <Section position="7" start_page="240" end_page="241" type="metho">
    <SectionTitle>
COMPUTATIONAL USE OF TIlE
STRATEGIES
</SectionTitle>
    <Paragraph position="0"> The strategies are currently ~mplemented on ~ test database composed of oblect descriptions from the encyclopedias. The representation of an object thus contains all the reformation included for that part:cular oblect m both encyclopedl~. The two  Tan process inforlation gets picked up tad printed out for t naive user. are the unique identifiers to the fruen corresponding to the nets-relations the program is ~racing.</Paragraph>
    <Paragraph position="2"> strategies presented dlctate what informatmn to snclude from the knowledge base, based on the constituency schema _or the process trace ~ shown in Figures 3,</Paragraph>
  </Section>
  <Section position="8" start_page="241" end_page="243" type="metho">
    <SectionTitle>
4 and SY
</SectionTitle>
    <Paragraph position="0"> Knowledge-based rep~seutat|on We use a frame-based knowledge representatmn \[Wasserman and Lebowitz 83; Wasserman 85} m which the basic frame represents an oblect These structures are the entitles in a generalizatmn hierarchy In additmn to the generalization, or instance-of links, there exist two additional kinds of links ioming entlties: part-of links, which indicate an entlty is a part of a larger structure, and relations, whlch convey mformatmn about spatlal or functional reiattonshlps Finally, there ,~re causal links between relations called meta.relations.</Paragraph>
    <Paragraph position="1"> 9Further work is needed to fully implement the schema predicates and add more descnptlve mlormatlon Implementlon of the adult encyclopedia strategy For an adult, the program {~ls the constituency schema, ~ shown In Figure 3An_ The predicates contained m the schema define the type of mformatmn to be taken from the database. The figure shows the final output. The entities are represented by thelr unique identlfier &amp;MENLX:, and the predicates are the starred items (e.g. *IDENTIFICATION'). The hypothetical english output is included in the comments.</Paragraph>
    <Paragraph position="2"> The identification predicate represents the more general concept of which the present ob|ect ts ~n mstance Because the test database mcludes only the mformatmn contained In the texts read, the hierarchy may not be complete for all objects. As ~n example, a transmitter was never defmed m terms of a more general device, and thus has no super-ordm~te The constituency predicate gives the components of ~a entity, if there are any lOSes \[McKeown 801 for details of ~ stmdar system.</Paragraph>
    <Paragraph position="3">  i nov the pro~rta taken each relation which can be dirlded into subnteps and ~racen ~hrough that each step. An this case, aBF.LS (P-VIBRATES) can be broken up into aBELS (P-MOVESoFOR|ARD) and aBEL7 (P-MOVES-BACAIARD).</Paragraph>
    <Paragraph position="5"> i The prosrus trace8 throug~ in the same manner for each relation ~avin~ substeps.</Paragraph>
    <Paragraph position="6"> FIKu~e $, Printou~ of the Process Trace (cont'd) Junior encyclopedia strategy For the junior, the strategy dictates to fol!ow the cause-effects links in the knowledge b~se ,n order t,o trace the process. In our representatlon, th~se causual links are named meta-relauons (In the figure, they are represented by the Identlflers &amp;:MRX. &amp;RELX correspond to the reiauons, l e the spatlal or funcUonal l,nks between entltles ). The program traces through the meta-relatlons, ptcklnK the process informatlon as shown m Fisure 4. When .~ relatlon can be broken into substeps, the program then traces through those sub-steps (see Figure S).</Paragraph>
    <Section position="1" start_page="241" end_page="243" type="sub_section">
      <SectionTitle>
Future Work
</SectionTitle>
      <Paragraph position="0"> There axe severM theoreticM msues that need to be addressed. In our test dat~ba.se, the problem of declding m what order relations occur does not arise.</Paragraph>
      <Paragraph position="1"> However, for an arbitrary database, knowmg where to begs describing a process may be more difficult Simllaxly, the process may not be as sequential ~s the ones we examined so fax, and, as a result, we plan on further study of how to organize the informaUon.</Paragraph>
      <Paragraph position="2"> Furthermore, in our test database, we don't need tc conszder how deep into the substeps the process description should go, but this Issue exists for an arbitraxy database. Finally, we have looked at the two ends of a spectrum (n~ve and expert), but, for users not at either of these ends, we must consider how to combine these strategies.</Paragraph>
      <Paragraph position="3">  We have started to address the problem of generating natural language for the descriptions. We have begun the augmentation of an English surface generator \]McKeown 82\] that, using * functional grammar \[Kay 79\], takes the output of the textual component to translate it into English sentences &amp;quot;'. However, how this program may interface with the strategies remains to be studied.</Paragraph>
    </Section>
  </Section>
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