PARASESSION ON TOPICS IN INYEZRACIXVE DISCOURSE 
INFLUENCE OF THE PROBLEM CONTEXT* 
Ar,avind K. Joshi 
Department of Computer and Infornmtion Science 
Room 268 Moore School 
University of Pennsylvania 
Philadelphia, PA 19104 
My consents are organized within the framework suggested 
by the Panel Chair, Barbara Grosz, which I find very 
appropriate. All of my conlnents pertain to the various 
issues raised by her; however, wherever possible I will 
discuss these issues more in the context of the "infor- 
mation seeking" interaction and the data base doma/n. 
The primary question is how the purpose of the inter- 
action or "the problem context" affects what is said 
and how it is interpreted. The ~ separate aspects 
of this question that must be considered are the func- 
tion and the domain of the discourse. 
I. Types of interactions (functions) : 
i. 1 We are concerned here about a computer system par- 
ticipating in a restricted kind of dialogue with a 
person. A partial classification of some existing 
interactive systems, as suggested by Grosz, is as 
follows. I have r~_named the third type in a somewhat 
more general fashion. 
Paz-ticipant Pl Participant P2 
(Computer system) (Person) 
Type A Expert Apprentice 
Type B Tutor Student 
Type C Information Information 
provider seeker 
(some sor~c of large 
and con~lex data base 
or knowledge base) 
Each type subsumes a variety of subtypes. For 
example, in type C, subtypes arise depending on the 
kind of infoz~ation ava~l~hle and the type of the user. 
(More on this later when we discuss the interaction 
of constraints on function and domain). 
I. 2 It should be noted also that these differ~_nt types 
are not r~ally completely independent; inf~tion 
seeking (Type C) is often done by the ap~tice (Type 
A) and student (Type B), and some of the expla/ning 
done by t-utor~ (Type B) is also involved in the Type 
C interaction, for exa~le, when P1 is trying to ex- 
plain to P2 the st-ruc%%u~e of the data base. 
1.3 The roles of the two par~cicipants are_ also not 
fixed completely. In the type C interaction, some- 
times P2 paz~ly plays the role of an ex~ (or at 
least appears to do so) believing that his/her ex~ 
advice may help the system answer the question more 
'easily' or 'efficiently'. For example l, in a pollu- 
tion data base P1 may ask: Has company A dumped any 
,~Bstes last week? and follow up with advice: 
arsenic first. In ~ expert-apprentice interactlon, 
the e xper~c's advice is assumed to be useful by the 
apprentice. In the data base domain it is not clear 
whether the 'expert' advice provided by the user is 
always useful. It does however provide infor~ration 
about the user which can be helpful in presenting the 
response in an appropriate manner; for example, if 
arsenic indeed was one of the wastes dumped, -~hen, per- 
haps, it should be lis:ed first. 
1.4 The interactions of the type we are concerned about 
here are all meant to aid a person in some fashion. 
Hence, a general characterization of all these t~/pes is 
a helping function. However, it is useful to distin- 
guish the types depending on whether an information 
or information sharin~ interaction zs involved. 
C--interaction is przmarily information seeking, 
although some sharing interaction is involved also. 
This is so because information sharing facilitates in- 
formation seeking, for example 2 , when Pl explains the 
structure of the data base to P2, so that P2 can engage 
in infor~nation seeking more effectively. Type A and 
B are more information sharing than infornmtion seeking 
interactions. 
i. S Another useful distinction is that type C interac- 
tion has more of a service function than types A and B 
which have more of ~ining function. Training in- 
volves more of information sharing, while service in- 
volves more of providing infornmtion requested by the 
user. 
2. Information about the user: 
2 .i By user we usually mean user type and nor a spe- 
cific user. User inforr~ation is essential in deter- 
minJ_ng expectations on the par~ of the user and the 
needs of the user. Within each type of interaction 
there can be many user types and the same infoz~nation 
may be needed by these different types of users for 
different reasons. For exan~le, in t-/pe C interaction, 
pr~_r~gist-ration iIlfor~ation about a course scheduled 
fox" the foz~chcoming t~ may be of interest to an in- 
st-cuctor because he/she wants to find out how popular 
his/her course is. On the other hand, the same data 
is useful to the regisrrer for deciding on a suitable 
r~x)m assigr~nent. The data base system will often pro- 
vide different views of the same data to different user 
types. 
2.2 In general, knowledge about the user is necessar~, 
at leas~ in the type C interaction in order to decide 
(i) how to present the requested information, 
(ii) what additional information, beyond that ex- 
plicitly requested, might be usefully pr~esented 
(this aspect is not independent of (i) above), 
(iii) what kind of responses the system should provide 
when the user's misconceptions about the domain 
* This work was par~ially supported by the NSF grant 
MCS79-08401. 
I ,~Bnt to thank Eric Mays, Kathy McKeown, and Bonnie 
Webber for their valuable conments on an earlier draft 
of this paper. 
31 
(i.e., both The ~crure and content of the 
data base, in short, what can be talked about) 
are detected. 
(More about this in Section 5). 
3. Conversational style: 
3.1 In the type C interaction, The user utterances (more 
precisely, user's Typewritten input) are a series of 
questions separated by the system's responses. By and 
large, the system responds to the current question. 
However, knowledge about the preceding interaction i.e., 
discourse context (besides, of course, the information 
about the user) is essential for tracking the "topic" 
and thereby deter~nining the "focus" in the current 
question. This is especially importa~nz for derer~Iining 
how to present the answer as well as how to provide 
appropriate responses, when user's misconceptions are 
detected. 
Type A and B interactions perhaps involve a much more 
structured dialogue where the sZru:rure has its scope 
over much wider stretches of discourse as co~d to 
the ai@\]ogues in the Type C interactions, which appear 
to be less strucru~. 
3.2 The type of interaction involved certainly affects 
the conversational style; however, li%-tle is known 
about conversational style in interactive man/machine 
communication. Folklore has it that users adapt very 
rapidly to the system's capabilities. It might be 
useful to compare this situation to that of a person 
talking to a foreigner. It has been claimed that 
natives talking to foreigners deliberately change their 
conversational style = (for example, slowing down their 
speech, using single words, repeating certain words, 
end even occasionally adopting some of the foreigner's 
style, etc. ). It may be that users rr~-at the computer 
system as an expert with respect to the knowledge of 
the domain but lacking in some communicative skills, 
much like a native talking to a foreigner. 
Perhaps it is misleading to Treat man/machine interact- 
ive discourse as just (hopefully better and better) 
approximations to h~ conversational interactions. 
No matter how sophisticated these systems become, they 
will at the ve.~y least lack the face to face interac- 
tion. It may be That there are certain aspects of 
these interactions that are peculiar to This modaliry 
and will always rema/m so. We seem to know so little 
about these aspects. These remarks, perhaps, belong 
.more to the scope of the panel on social context than to 
the scope of this panel on the problem context. 
4. Relation of expectations and functions: 
~.i In the information seeking interaction, us,~11y, 
the imperative force of the user's questions is to have 
the system bring it about that The use~- comes to know 
whatever he/she is asking foP. Thus in asking the 
question Who is r~istered in CIS 591? the user is in- 
terested in knowing who is registered in CIS 591. The 
user is normally not interested in how the syst~n got 
the answer. Ln the Type A and B in--actions the 
imperative force of a question from the user (apprentice 
or student) can either be the same as before or it can 
have the imperative force of making the system show the 
user how the answer was obtained by the system. 
4.2 ~.n the data base domain, although, primarily the 
user is interested in what the answer is and no~ in how 
it wa obtained, this need not be the case always. 
Somet..~s the user would like to have the answer accom- 
panied by how it was obtained, the 'access paths' 
through the--~ta base, for example. 
4.3 Even when only the what answer is expected, often 
the presentation of the answer has to be accompanied by 
some 'supportive' information to make the response use- 
ful to the user 4 . For exa~le, along with the student 
name, his/her department or whether he/she is a Eradua1~ 
or under~duate student would have to be stated. If 
telephone numbers of students are requested then along 
with the telephone numbers, the corre_sponding names of 
students will have to be provided. 
S. Shared knowledge and beliefs: 
5.! The shared beliefs and goals are embodied in the 
system's knowledge of the user (i.e., a user model). 
It is important to assume that not only the system has 
the knowledge of the user but that the user assumes 
that the system has this knowledge. This is very 
necessary to generate appropriate cooperative responses 
and their being correctly understood as such by the 
user. In or~ina_-y conversations this type of knowiec~e 
could lead to an infinite regmess and hence, the need 
to require the shared knowledge to be ',u/rual knowle~e'. 
However, in the current da~a base systems (and even in 
the expert-epvrentice and tutor-student interactions) 
I am not aware of situations that truly lead to some of 
the well krK~an prDblems about 'mutual knowledge' 
5.2 As regards the knowledge of the data base itself 
(both structure and content), the system, of course, 
has this knowledge. However, it is not necessary 
that the user has this knowledge. In fact very often 
the user's view of The data base will be different 
from the system's view. For large and complex data 
bases this is more likely to be the case. The system 
has to be able to discern the user's view and present 
the answers, keeping in mind the user's view, ~Tuile 
insuring that his/her view is consistent with the 
system's view. 
S. 3 When the system recognizes some disparity between 
its view and the user's view, it has to provide appro- 
priate corrective responses. Users' misconceptions 
could be either extensional (i.e., about the content 
of the data base) or intensional (i.e., about the 
structure of the data base) ~ . Note that the ex- 
tensional/inTensional distinction is from the point 
of view of the system. The user may not have made 
the distinction in that way. Some simple examples of 
corrective r~_sponses are as follows. A user's ques- 
tion: Who took CIS 591 in Fall 19797 presumes that 
CIS 591 was offered in Fall 1979. If ~his ~as not 
the case then a response None by the system would be 
misleading; rather the response should be that CIS 591 
was not offered in Fall 1979. This is an instance of 
an extensional failure. An example of intensional 
failure is as follows. A user's question: How man 7 
under~aduates taught courses in Fall 19797 pr~su~es 
(among other things) that undergraduates do teach 
courses. This is an intensional presumption. If it 
is false then once again an answer None would be mis- 
leading; rather the response should--~ that under ~ 
graduates are nor perm ~Ted to teach coUrSes, faculty 
members teach courses, and graduate students teach 
courses. The exact nature of this response depends 
on the s~:rucrure of the data base. 
5. Co~lexir~ of The domain: 
6 .i Iu each type of interaction the complexity of the 
interaction depends both on the nature of the interac- 
tion (i.e., function) as well as the domain. In many 
ways the complexity of the interaction ultimately seems 
to depend on the cc~nplexity of the domain. If the 
task itself is not very complex (for example, boiling 
water for tea instead of assembling a pump) the task 
oriented expert-apprentice interaction cannot be very 
complex. On the other hand data base interaction 
which appear to be simple at first sight become in- 
creasingly complex when we begin to consider (i) dyna- 
mic data bases (i.e., they can be updated) and the 
associated problems of monitoring events (ii) data 
bases with n~itiple views of data, (iii) questions 
whose answers z~equiz~ the system to make fairly deep 
inferences and involve computations on the data base 
i.e., the answers are not obtained by a straigbtfor%mz~ 
retrieval process, etc. 
NOTES: 
i. As in the PLIDIS system described by Genevieve 
2. As in Kathy McKeown's current work on gene_~ating 
descriptions and explanations about data base 
st-~ucrure. 
3. For exa~le, by R. Rammurri in hem talk on 
'Strategies involved in talking to a foreigner' 
at the Penn Linguistics Forth 1980 (published in 
Penn Review of Linguistics, Vol. 4, 1980). 
~. Many of my comments about supportive information 
and corrective responses when misconceptions about 
the ccntent and the stTucrure of the data base 
are detected are based on the work of Jerry 
Kaplan and Eric Mays. 

