ON THE INDEPENDENCE OF DISCOURSE STRUCTURE 
AND SEMANTIC DOMAIN 
Charlotte Linde ~ J.A. Goguen + * 
I. THE STATUS OF DISCOURSE STRUCTURE 
Traditionally, linguistics has been concerned with units 
at the level of the sentence or below, but recently, a 
body of research has emerged which demonstrates the 
existence and organization of linguistic units larger 
than the sentence. (Chafe, 1974; Goguen, Linde, and 
Weiner, to appear; Grosz, 1977; Halliday and Hasan, 1976; 
Labov, 1972; Linde, 1974, 1979, 1980a,198Cb; Linde and 
Goguen, 1978; Linde and Labov, 1975; Folanyi, 1978; 
Weiner, 1979.) Each such study raises a question about 
whether the structure discovered is a property of the 
organization of Language or whether it is entirely a 
property of the semantic domain. That is, are we discov- 
ering general facts about the structure of language at a 
level beyond the sentence, or are we discovering 
particular facts about apartment layouts, water pump 
repair, Watergate politics, etc? Such a crude question 
does not arise with regard to sentences. Although much 
of the last twenty years of research in sentential 
syntax and semantics has been devoted to the investigat- 
ion of the degree to which syntactic structure can be 
described independently of semantics, to our knowledge, 
no one has attempted to argue that all observable 
regularities of sentential structure are attributable to 
the structure of the real world plus general cognitive 
abilities. Yet this claim is often made about regular- 
ities of linguistic structure at the discourse level. 
In order =o demonstrate that at leas= some of the 
structure found at the discourse level is independent 
of the structure of the semantic domain, we may show 
that there are discourse regularities across semantic 
domains. As primary data, we will use apartment layout 
description, small group planning, and explanation. 
These have all been found to be discourse units, that 
is, bounded linguistic units one level higher than the 
sentential level, and have all been described within 
the same formal theory. It should be noted that we do 
not claim that the structures found in these discourse 
units is entirely independent of structure of the 
semantic domain, because of course the structure of the 
domain has some effect. 
2. TREE TRANSFORMATIONS IN DISCOURSE PRODUCTION 
The discourse units mentioned above have all been found 
to be tree structured. This is a claim that any such 
discourse can be divided into parts such that there 
are significant relations of dominance among these parts. 
These trees can be viewed as being constructed by a 
sequence of transformations on an initial empty tree, 
with each transformation corresponding to an utterance 
by participants, which may add, delete, or move nodes 
of the tree. The sequence of transformations encodes 
the construction of the discourse as it actually 
proceeds in time. 
We now turn to a discussion of the discourse units 
which have been analysed according to this model. 
* Structural Semantics, P.O. Box 707, Palo Alto, 
California 94302. 
+ SRI International, 333 Ravenswood Ave., Menlo Park, 
California 94025. 
2.1 SPATIAL DESCRIPTIONS AS TOURS 
In an investigation of the description of spatial 
networks, speakers were asked to describe the layout of 
their apartment. The vast majority of speakers used a 
"tour strategy," which takes the hearer on an imaginary 
tour of the apartment, building up the description of 
the layout by successive mention of each room and its 
position. This tour forms a tree composed of the entry 
to the apartment as root with the rooms and their 
locations as nodes, and with an associated pointer 
indicating the current focus of attention, expressed by 
unstressed you. 
It might be argued that the tree structure of these 
descriptions is a consequence of the structure of 
apartments rather than of the structure of discourse. 
However, there are apartments which are not tree 
structured, because some rooms have more than one 
entrance, thus allowing multiple routes to the same 
point; but in their descriptions, speakers traverse only 
one route; that is, loops in the apartment are always 
cut in the descriptions. \[ Thus, although some of the 
tree structure may be attributable to the physical 
structure being described, some of it is a consequence 
of the ease of expressing tree structures in language, 
and the difficulty of expressing graph structures. 
The tree structure of apartment descriptions is construc- 
ted using only addition transformations, and pointer 
movement transformations (called "pops" in tinde and 
Goguen (1978)) which bring the focus of attention back 
from a branch which has been traversed to the point of 
branching. The construction of the tree is entirely 
depth first. 
2.2 SPATIAL DESCRIPTIONS AS MAPS 
In describing apartment layouts, there is a minority 
strategy, used by 4% of the speakers (3 out of 72 cases 
of the data of Linde (1974)) describing the layout in 
the form of a map. The speaker first describes the 
outside shape, then sketches the internal spatial 
divisions, and finally labels each internal division. 
This strategy can also be described as a tree 
construction, in this case, a breadth first traversal 
with the root being the outside shape, the internal 
divisions the next layer of nodes, and the names of 
these divisions the terminal nodes. Because there are 
so few example, it is not possible to give a detailed 
description of the rules for construction. 
2.3 PLANNING 
We have argued that the structure of apartment layout 
descriptions is not entirely due to the structure of the 
semantic domain; however, a question remains as to 
whether it is the restriction to a limited domain which 
permits precise description. To investigate this, let 
us consider the Watergate transcripts, which offer a 
spectacularly unrestricted semantic domain, specifically 
those portions in which the president and his advisors 
engage in the activity of planning. (Linde and Goguen, 
1978). Planning sessions form a discourse unit with 
"\[ In more mathematical language, the linear sequence of 
rooms is the depth first traversal of a minimal spanning 
tree of the apartment graph. 
35 
discernable boundaries and a very precisely describable 
internal structure. Although we can not furnish any 
detailed description of the semantic domain, we can be 
extremely precise about the social activity of plan 
construction. 
Because the cases we have examined involve planning by a 
small group, the tree is not constructed exclusively by 
addition, as are the types discussed above. Deletion, 
substitution, and movement also occur, as a plan is 
criticised and altered by all members of the group. 
Z.4 EXPLANATION 
A discourse unit similar to planning is explanation. 
(Weiner, 1979; Goguen, Linde and Weiner to appear.) (By 
explanation we here include only the discourse unit of 
the form described below; we exclude discourse units 
such as narratives or question-response pairs which may 
socially serve the function of explanation.) Informally, 
explanation is that discourse unit which consists of a 
proposition to be demonstrated, and a structure of 
reasons, often multiply embedded reasons, which support 
it. The data of this study are accounts given of the 
choice to use the long or short income tax form, 
explanations of career choices, and material from the 
Watergate transcripts in which an evaluation is given 
of how likely a plan is to succeed, with complex 
reasons for this evaluation. 
Like apartment descriptions and small group plan- 
ning, explanation can be described as the transforma- 
tional construction of a tree structure. Since in the 
casesexauLined, a single person builds the explanation, 
there are no reconstructive transformations such as 
deletion or movement of subtrees; the transformations 
found are addition and pointer movement. Pointer 
movement is particularly com~lex in this discourse unit 
since explanation permits embedded alternate worlds, 
which require multiple pointers to be maintained. 
Explanation structure appears to be the same in the 
three different semantic domains, suggesting that the 
discourse structure is due to genral rules plus a 
particular social context, rather than being due to the 
structure of the semantic domain. 
3. CRITERIA FOR EVALUATING DISCOURSE STRUC%~/RES 
The criticism might be made of these tree structures 
that an analyst can impose a tree structure on any 
discourse, without any proof that it is related to 
what the speaker himself was doing. We would claim that 
although we have, of course, no direct access to the 
cognitive processes of speakers, there are two related 
criteria for evaluating a proposed discourse structure. 
3. I TEXT MARKING 
One criterion for Judging the relative naturalness of a 
particular analysis is the degree to which the text 
being analysed contains markers of the structure being 
postulated. Thus, we have some confidP-ce that the 
speaker himself is proceeding in terms of a branching 
structure when we find markers like "Row as you're 
coming into the front of the apartment, if you go 
straight rather than go right or left, you come into a 
large living room area," or "On the one hand, we could 
try ..." The opposite case would be a text in which 
the division postulated by an analyst on the basis of 
some a priori theory had no semantic or syntactic 
marking in the text. 
3.2 FRUITFULNESS OF THE ANALYSIS 
A second criterion is whether some postulated 
structure is fruitful in generating further suggestions 
for how to explore the text. Thus, the tree analyses of 
apartment layout descriptions, planning, and explanation, 
give rise to questions such as how various physical layouts 
are turned into trees, how trees are ~raversed, the social 
consequences of particular transfoz~l~ions, the apparent 
psychological ease or difficulty of various transformations, 
the relation of discourse structure to syntactic structure, 
etc. (see Linde and Goguen, 1978) By contrast, an 
unfruitful analysis will give rise to few or no interesting 
research questions, and will not permit the analyst to 
investigate questions about the discourse unit which he or 
she has reason to believe are in,cresting. 
4. GENERAL PRINCIPLES OF DISCOURSE STRUCTURE 
Given that ~hese postulated structures are useful models 
of what speakers do, we may ask how it is that speakers 
produce texts with these structures. It is known that 
children must learn to produce well-formed narratives. 
It might be hypothesized that each discourse unit must 
be separately learned, and that each has its own unrelated 
set of rules. However, there is evidence that there are 
verT general rules for discourse construction, which hold 
across discourse units, and which can be used ~o construct 
novel discourse units. The test case for such a 
hynuthesls is the production of a discourse unlt whlch 
is not a part of speakers' ordinary repetolre, but 
rather, is made up for the occasion of the experiment. 
Such an experiment was performed by asking people to 
describe the process of getting themaelves and their 
husbands and children off to work in the morning. (Linde, 
in preparation) These "morning routines" are typically 
well-structured and regular; everyone appears to do 
them the same way. We know that the speakers had never 
produced such discourses before, since we never in 
ordinary discourse hear such extended discussions of 
the details of daily llfe. (Even bores have their 
limits.) Therefore, the regularities must be the 
product of the intersection of a particular real world 
domain, in this case, multiple parallel activities, with 
very general rules for discourse construction. 2 
4.1 META-RULES OF DISCOURSE STRUCTURE 
We are by no means ready to offer a single general 
theory of discourse structure; that must wait until 
a sufficiently large number of discourse types has been 
investigated in detail. However, the following rules 
have been observed in two or more discourse units, and 
it is rules of this type that we would llke to investl- 
gate in other discourse units. 
\[. The most frequent subordinator for a given 
discourse unit will have the most minimal 
marking in the text, most frequently being 
marked with lexical and. Moreover, it will not 
be necessary to establish this node before 
beginning the first branch, but only when the 
return to the branch point is effected. 
2. All other node types which subordinate two or 
more branches, such as exclusive or or 
conditional, must be indicated by markers in 
the text before the first branch is begun. 
3. Depth-first traversal is the most usual strategy. 
4. Pop markers are available to indicate return to 
a branch point or higher node; it is never 
necessary to recapitulate in reverse the entire 
traversal of a branch. 
Z This is interesting for the light which it sheds on 
natural structures for the description of concurrent 
activities. 
36 
5. CONCLUSIONS 
The reason for being interested in regularities of 
• discourse structure, particularly regularities which hold 
across a number of discourse types, is that they suggest 
universals of what is often called "mind," and, more 
practically, they also suggest features which might be 
part of systems for language understanding and production. 
Indeed Welner (to appear) has constructed a system for the 
production of explanations of U.S. income tax law based 
on the transformational theory of explanation discussed 
in section 2.4. There is, moreover, the possibility of 
designing meta-systems, which might be programmed to 
handle a variety of discourse types. 
ACKNOWLEDGEMENTS 
We would like to thank R. M. Burstall and James Weiner 
for their help throughout much of the work reported in 
this paper. We owe our approach to discourse analysis 
to the work of William Labor, and our basic orientation 
to Chogyam Trungpa, Rinp~che. 
REFERF.NCES 
Chafe, Wallace, 1974. Language and Consciousness. 
Language. Vol. 50, 111-133. 
Goguen, J.A., Charlotte Linde, and James Weiner. to 
appear. The Structure of Natural Explanation. 
Grosz, Barbara J. 1977. The Representation and Use 9f 
Focus in Dialogue Understanding. SRI Technical Note 151. 
Hal~iday, M.A.K. and Ruqaiya N. Hasan, 1976. Cohesion 
in English, Longman, London. 
Labor, William, 1972. The Transformation of Experience 
into Narrative Syntax, in Language in the Inner City, 
Philadelphia, University of Pennsylvania Press. 
Linde, Charlotte, 1974. The Linguistic Encoding of 
Spatial Information. Columbia University, Department of 
Linguistics dissertation. 
Linde, Charlotte, 1979. Focus of Attention and the Choice 
of Pronouns in Discourse, in Syntax and Sem~ntlcs, Vol.12 
Discourse and Syntax~ ed. Talmy Givon, Academic Press, 
New York. 
Li~de, Charlotte, 1980a. The Organization of Discourse, 
in The English Language in its Social and Historical 
Context ed. Timothy Shopen, Ann Zwlcky and Peg Griffen, 
Winthrop Press, Cambridge, Massachusetts. 
Linde Charlotte, 1980b. The Life Story: A Temporally 
Discontinuous Discourse Type, in Papers From the Kassel 
Workshop on Psycholingulstic Models of Production. 
Linde, Charlotte, in preparation. The Discourse Structure 
of the Description of Concurrent Activity. 
Linde, Charlotte and J.A. Goguen, 1978. The Structure 
of Planning Discourse, Journal of Social and Biological 
Structures, Vol. \[, 219-251. 
Linde, Charlotte and William Labor, 1975. Spatial 
Networks as a Site for the Study of Language and Thought, 
Language , Vol. 51, 924-939. 
Polanyi, Livia, 1978. The American Story. University of 
Michigan Department of Linguistics dissertation. 
Weiner, James, 1979. The Str~cture of Natural 
Explanation: Theory and Application. System 
Development Corporation, SP-4035. 
Welner, J. BLAH: A System Which Explains its Reasoning, 
tO appear in Artificial Intelli~ence. 
37 

