ON MODES OF DEPINITE REFERENCE: AN APPLICATION TO THE 
INTERACTION WITH DATABASE SYSTEMS 
Genevieve Bsr~y-Rogghe 
Temple University, CI8 Department; 03824 
Philadelphia, PA 19122, U.S.A. 
Identifying the referent of a singular definite term in 
a database query essentially consists in detemining its 
extension in the database by applying the Ruassllian truth 
conditions for definite descriptions. However, most definite 
descriptions are "incomplete" in that the description itself 
does not contain the uniquely specifying conditions but it 
should be au~nented by features derived from the situation or 
discourse context. Most work in AI in this field has con- 
centrated on how to delimit the relevant contextual features 
(see, for example, the work on anapho~o reference and focus- 
sing by Webber 78, Sidner 77 and Grosz 76). This paper 
addresses certain aspects of the theory of definite reference 
which, though extensively treated in the literature on lan- 
guage philosophy, have been rather neglected in the design 
of natural language processing systemae. 
Some of the ambiguities of definite reference derive 
from the fact that a definite description may denote some 
unique individual in the world satisfying the specification 
or some individual the speaker has in mind who may or may not 
coincide with the former (ie the "referential" versus the 
,,attrib~tive n mode of reference). Furthelqnore~ the speaker 
may intend the hearer to interpret the rsfe~cl~ expression 
in either a "value laden" or a "value free" mode (cfr Ba~- 
wiee/Psx-~y 80). In the former mode the sentence is given 
- 32 - 
f 
a secondary interpretation by substitutin~ in it the entity 
fulfilling the description. This raises such issues as to 
whether definite descriptions may be used to inform as well 
as to refer (see Joshi 78). The first part of the paper 
attempts to characterize the phenomena variously referred to 
by such terms as intension/extenston, de ditto/de re, 
attrlbutlve/referentlal, value-free~value-laden... Some of 
these phenomena are to be accounted for on the semantic 
level of representation whereas others are deemed to belong 
to the pra~natic level, 
The second part of the paper examines which of the 
modes of definite reference distinguished in paz~t I are 
manifested in the interaction with a database system and how 
they can be recognized by the natuxal language interface. The 
standard procedure for definite reference identification is 
to exclude generic and "intensional" uses; to assume identity 
between the referent the speaker believes fulfills the 
description and the actual referent and to uniformly impose 
a value-laden interpretation mode, The following examples 
illustrate some other modes of reference which should receive 
adequate treatment in a natural language interface extending 
its capicity beyond the mere retrieval of factual informat- 
ion. 
The generic mode of reference is not always obviously 
distinguishable from the attributive mode as shown by (1) 
and (2), reepectlvely~ 
(1) How long is the flight from Boston to Chicago? 
(2) How many passengers were on the flight from 
Boston to Chicago? 
The semantic interpretation of the definite article in 
(1) corresponds to the universal quantifier whereas Xn (2) 
it corresponds to the iota-operator. In contrast to the gen- 
eric mode, a definite description is used "intenaionally" 
when the substitution of its extension in ~he sentence may 
alter the truth value. This is the case in referentially 
- 33 - 
opaque contexts. It hss been pointed out by Kaplan/Davidson 
81 that certain update commands such as (3) may be referent- 
ially opaque: 
(3) Change the teacher of CIS 234 to Dr. Smith. 
The difference between the attributive and the referent- 
ial uses, on the other hand, may be illustrated by the differ- 
ent replies (4a) end (4b), respectively, to query (4): 
(4) Is there a car parked under the big cherry tree? 
(4a) No. There is no cherry tree in the scene. 
(4b) Yes. But the tree you are referring to is an oak. 
In the referential mode of reference the hearer has an 
independent way of identifying the referent, usually through 
locating him in time and space. In this mode the description 
serves a dual function of referring and of describing. The 
referential mode is only likely to occur when interacting 
with a database consisting of visual objects displayed on a 
screen (as in the SRI and HAM-RPM projects). In the attribut- 
ive mode the description refers to whichever entity fulfills 
the specification at a particular index. The referential/ 
/attributive distinction is not to be explained as a scope 
ambiguity (cfr the re/de ditto readings) but rather both 
readings should receive the same semantic interpretation, the 
distinction being accounted for on the pragmatic level (see 
further). 
Of particular importance to natural language interaction 
in a system that ales at a high degree of "cooperativeness" 
is the distinction between the value-free and value-laden 
interpretation modes, from the point of view of the hearer. 
Consider the following alternative system replies (Sa) and 
(5h) to query (5). In (Sa) the definite description was 
value-laden, as is the standard practice, whereas the value- 
-free interpretation indicated by (Sb) seems to be more 
appropriate to the user's intentions: 
- 34 - 
(5) U: Does the head of the CIS department earn more 
then the head of the Philosophy department? 
S: Yes 
U: Why? 
(5a) S: Because Dr. Jones has more dependents than 
Dr. Smith 
(Sb) S: Because computer science is better remunerated 
than philosophy • 
In order to retrieve the answer the extension of the 
description has to be determined in both cases but in (Sb) 
the ingredients of the descriptive expression were retained 
for further processing. This raises such pragmatic issues as 
why a speaker chooses a particular description to refer to an 
entity and what clues might guide the hearer as to the in- 
tended interpretation stratbgy. 
The third part of the paper gives an outline on how to 
interpret these modes in the system. The approach taken is 
that certain modes should be treated as pra~atio phencaema 
rather than as semantic ones. Atthe semantic level a language 
processing system should produce a context-independent inter- 
pretation of what a speaker means by an utterance. The prag- 
matic level deals with what the speaker Intends the hearer to 
imfer from his utterance. At the semantic level of representat- 
ion the Russellian truth conditions for definite reference are 
applied, where appropriate. These determine the "semantic 
referent" which is defined by the conventions of the language; 
the "speaker's referent", on the other hand, is the object 
which the speaker believes fulfills the conditions for being 
the semantic referent (see Kripke 77). This paper attempts to 
specify the notion of "speaker's referent" in terms of refer- 
ence as a speech act. For example, a condition for felicitous 
reference in the referential mode is that the speaker believes 
that the referent satisfies the description and also that he 
believes the hearer believes In the "Justification" for the 
description (cf~ Cohen/Perrault 81). It wall be shown that in 
- 35 - 
certain contexts definite reference involves other speech acts 
besides refezTlng such as informing, describing, expla~ning... 

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