SYSTEMIC GRAMMAR IN COMPUTATION: 
THE NIGEL CASE 
Christian M.I.M. Matthiessen, 
USC/Information Sciences Institute 
1 INTRODUCTION 
Computational linguistics needs grammars for several different 
tasks such as comprehension of text, machine translation, and 
text generation. 1 Clearly, any approach to grammar 2 has 
potentially something to offer computational linguistics, say for 
parsing or text generation (and, by the same token, there is a 
potential benefit from an application within computational 
linguistics for each approach, cf. \[Fawcett 80\]). However, it is 
equally clear that some approaches have much more to offer than 
others. Here I will take a look at Systemic Linguistics 3 in the 
service of computational linguistics tasks, concentrating on a 
1This research was Supported by the Air Force Office of Scientific Research 
Contract NO. F49620-79.C.0181. The views, and conclusions contained in this 
document are those of the authors and should not be interpreted as necessarily 
representing the official policies or endorsements, either expressed or implied, of 
the Air Force Office of Scientific Research of the U.S. Government. I am very 
grateful to William Mann for many helpful comments on various versions of this 
paper; much of the discussion builds on work by him. f am also deeply indebted to 
Michael A.K. Hallida~'; I have profited from and drawn heavily on his insights about 
English grammar and semantics and the systemic framework. I am solely 
responsible for all errors. 
2There are now in the early 80s a great number of grammatical mechanisms 
around -- witness for example the 1979 Milwaukee conference on current 
alternative approaches to syntax where around fourteen alternatives were 
presented (see \[Moravcsik & Wirth 80\]). a collecbon which is only a sample, 
leaving out many current approaches. The term grammar is used in its traditional 
sense in systemic linguistics: it subsumes both syntax and morphology. This use 
contrasts with the more recent one where grammar subsumes semantics, syntax, 
morphology, and phonology. 
3There are few grammatical mechanisms that have been developed within a 
framework with as impressive a tradition as Systemic Linguistics and with as wide a 
scope. The systemic framework is not just a non.transformational alternative to 
Chomsky's transformational grammar. It is different from Chomskyan work at the 
level of framework, not only at-the level of mechanism and notation. Systemic 
linguists ask questions like "How does communication succeed?", "What are the 
relations between context and language use?". "What can a speaker of English do 
grammatically to achieve a particular purpose?". "What are the options for 
expressing grammatically a particular range of meanings?", "What functions does 
language serve?" and so on. These are questions that are crucial to the success 
ot for example a text generation system. One consequence of questions of this 
type has been in Systemic Linguistics that text as a communicative unit is taken to 
be the basic linguistic unit rather than the sentences that are used to express texts, 
see \[Hasan 78\] and \[Hasan 79\]. Obviously, this view has far-reaching effects on 
the .',)nception of grammar. The systemic conception of language draws on 
continental European work, the British tradition started by Firth, and American 
anthropological linguistics. It has much to offer at a time when communication is 
beginning to assert itself as a central organizing notion in linguistic research 
instead of the much more limited notion of (primarily syntactic) competence that 
received so much attention for a long time in the CoOs. but began to lose its 
ap~,arent attractiveness in the 70s. For discussion of systemic grammar, see e.g. 
\[Ha!liday 69\], \[Halliday 76a\]. \[Hudson 76}. \[Davey 79\], \[Berry 77\], \[Fawcett 80\], and 
\[Matthiessen 83\]. 
large computational systemic grammar for text generation (Nigel) 
that is currently being developed. 
1.1 What can systemic linguistics offer? 
The question I will try to answer in this paper is what systemic 
linguistics can offer computational linguistics. Since the answer is, 
I think, far too long for a short discussion, I will let a more specific 
question represent the general question here: What can systemic 
linguistic accounts of grammar and semantics offer computational 
linguistics in the area of text generation? This question excludes 
for example the use of systemic grammar in parsing -- see 
\[Winograd 72\] -- and the large systemic body of work on 
discourse organization (see in particular \[Halliday & Hasan 76\], 
\[Hasan 78\], \[Hasan 79\], \[Halliday & Hasan 80\], \[Martin 83\], and 
\[Butler 83\]). 
The text generation task raises a number of demands on the 
grammatical component, Very roughly and generally stated, they 
amount to generating in conformity with diverse needs, such as 
the need for denotational appropriateness and the need for fluent 
text. There is no published general solution to the problem of 
controlling the grammar to generate in conformity with diverse 
needs. The discussion here continues and elaborates parts of 
\[Matthiessen 81\], 
1.2 Systemic functionalism as a contribution 
A cornerstone in systemic linguistics as developed by M.A.K. 
Halliday and others is systemic functionalism. 4 Grammar is to be 
investigated and interpreted in terms of the purposes it fulfills. Its 
organization is a function of these higher-level considerations. 
Apart from guiding research in systemic linguistics, this 
functionalism has been important in the design of systemic 
grammar. I will identify two design properties characteristic of 
systemic grammars that make them well suited to deal with the 
demands, better than grammars that are not designed to reflect 
the functionalism that the two ProPerties stem from. The two 
4There are also strictly formal considerations having to do with the notation 
used. These have been more central in work on e.g. Lexical Functional Grammar, 
Functional Unification Grammar. and Generalized Phrase Structure Grammar. The 
results may or may not generalize to Systemic Grammar; that is a matter for future 
discussion. 
155 
properties have to do with the organization of grammar and with 
the process of sentence generation; they constitute factorings of 
the sentence generation task. One is a factoring into a process of 
controlled choice and a process of structure specification as a 
consequence of choices made. This factoring is due to the need 
to represent the organization of grammar in its role as a resource 
for communicative needs. The other is a {'actoring of the 
grammatical resources into domains that serve different purposes 
(what will be called the mete-functional factoring). I will use Nigel 
to illustrate how they work and what their value is in text 
generation Systems. I will also present a completely new addition 
to systemic grammar, the so-called chooser framework, developed 
in the context of the text generation task. 5 
1.3 Organization of the discussion 
First, I will sketch the steps in the process of text generation so 
that the role grammar has to play can be identified (section 2). The 
rest of the paper illustrates how systemic functionalism enables 
grammar to cope with tasks its role in the text generation process 
entails. I will use the generation of a particular text realized by a 
single sentence, Had Sir Christopher Wren been going to build a 
cathedra/ ever since his youth?, as a way of illustrating and 
organizing the discussion. 
2 THE TEXT GENERATION PROCESS 
In this presentation of text generation. I will follow an expository 
design by William Mann (see \[Mann 83\]). The model of text 
generation he gives an overview of is called Penman. It has been 
designed for monologue only, without for example any facilities for 
comprehension. However, although Penman cannot take part in a 
conversation, I will present an example that corresponds to a turn 
in a dialogue; Penman will be assigned the task of asking a 
question in this illustration. The reason for doing this is purely 
illustrative; the task of asking a question is a concise way of 
bringing out a number of features of the grammar, 
Assume that a need for a text has arisen. In a conversation 
about Sir Christopher Wren. the need arises to know whether 
there was a plan for him to build a cathedral sometime after the 
5Functionalism in linguistics will hopefully be reconciled with goal reasoning as 
it has developed in computational linguistics and AI. The term function has two 
related meanings in current lingu=stics, in addition to its strictly mathematical 
sense. One is "mete-function,'" which can be defined as the purpose or goal 
-- effect considerations that defines a particular component of the grammar. The 
second meaning of function is what Halliday has calted "micro-function". This type 
is the one that figures in traditional grammar .- subject, object, etc. -- and more 
• ,c~,nt!,! in for example Relational Grammar, Case Grammar, and Lexical 
Functional Grammar Conceptually, micro-functions are very much like roles or 
slots used in semantic netS, (Micro vs. macro is here simply a distinction between 
small and big; meta means that the functions are on another plane, not part of the 
structure, in this way it is the same "mete" we find in for example "mete- 
language".) For an interesting discussion of the development of mete-functions 
and mi:ro-functions out of a set of macro-functions in early child language, see 
{Hal!iday 75}. For some discussion of functional grammar, see e.g. {Halliday 69\]. 
\[Halliday 74\], \[Fawcett 80\], and \[Dik 78\]. 
time when he was still a youngster. The task of the text generator 
is to satisfy this need. (As we will see, one way of meeting this 
need is to ask Had Sir Christopher Wren been going to build a 
cathedral ever since his youth?,) Three processes, Acquisition, 
Planning, and Sentence generation, work in text generation 
towards meeting the need. 
2.1 Steps in the text generation process 
Given the need for text, the text generator identifies the goals 
that the text should pursue and acquires the information 
necessary to pursue it. This process is supported by a knowledge 
base. The goal is roughly that the addressee recognize that the 
information desired has been requested; in this case, we want to 
find out whether Sir Chris had been going to build a cathedral or 
not. 
Next, there is a process of text planning. In response to the goal 
for the text and the information acquired, a plan to achieve the 
goal is created. The planning process uses a rhetoric of text 
organization to create the text plan. 
The plan consists of (among other things) conceptual loci (at 
least one), each of which corresponds roughly to, an independent 
clause. 6 In the present example, a text with one such locus is 
planned, a locus we can call CATHEDRAL-BUILDING. It is up to 
sentence generation to realize this plan, i.e., to find a wording 
for it. The process of sentence generation does this, relying on 
grammar as its resource. The remainder of the paper deals with 
this part of the text generation process. The grammar I will draw 
on for the rest of the discussion is the Nigel grammar, the systemic 
text generation grammar mentioned earlier. 7 
2.2 The task for sentence generation 
The sentence generation process can start when there is a fully 
specified local plan for CATHEDRAL-BUILDING in the text plan for 
an independent clause. Such a plan includes among other things: 
. A pointer to the process aspect of CATHEDRAL. 
BUILDING, called BUILDING in our example. 
• A specification of the local speech act, here called 
BUILDING.QUESTION; see the discussion of Mood 
below. 
• A plan for temporal relations; cf. the discussion of 
Tense below. 
6A traditional distinction between clause and sentence is maintained in systemic 
linguistics. A sentence can be defined simply as a complex of clauses, related by 
coordination or subordination. 
7Although the text generation process can conveniently be factored into the 
three subproceasas identified above, these subproceases are not necessarily 
senally arranged. There is one additional process, a orocess of improvement. For 
instance, the quality of the output of sentence generation is evaluated and then, 
based on this evaluation, changes in the plan are proposed. 
156 
= 
-Possibly a specification of a specific conceptual 
context, defined temporally, spatially, in terms of 
purpose, or in some other way, to be indicated as a 
part of the organization of the text in terms of 
conceptual contexts. There is no such specification 
for the present example. 
• Possibly a specification of a conjunctive relation (like 
contrast, enumeration, temporal sequence, 
disjunction, and cause) to be expressed. There is no 
such specification for the present example. 
A list such as this represents expressive demands, all of which 
the grammar of the sentence generation process has to cope with, 
but it imposes no structuring or factoring of this process. The task 
of the grammar and its semantics is to impose an organization of 
and find a wording for the material relevant to the local plan. 
Consequently, it is quite helpful if the grammar of the sentence 
generation process is organized in such a way that the process 
can be decomposed into manageable subprocesses. 
In what follows, I shall show how there is a natural factoring of 
the sentence generation process that derives from the systemic 
organization of a grammar. As we will see, this factoring is due to 
the research programme (a consequence of systemic 
.~unctionalism) in systemic linguistics to uncover the functional 
• organization of grammar and semantics and to reflect it in 
systemic notation. 
3 SYSTEMIC FACTORING OF SENTENCE 
GENERATION 
The design of systemic grammar is the result of a long-term 
effort to create a grammatical framework that reflects the 
functional organization of grammar. The important point to note 
here is that the organization of systemic grammar leads naturally 
to a factoring of the sentence generation process. In other words, 
the systemic factoring of the sentence generation process is due 
to the organization of systemic grammar, 
There are two simultaneous factorings that cross-cut: 
1. The process of structure building is factored into two 
processes, each of which with its own notation: The 
process of choosing among grammatical alternatives 
(section 4.1) and the process of realizing, or re- 
expressing, a particular choice as a specification of a 
fragment of grammatical structure (section 4.2). 
2. The statements of grammatical choice, realizations of 
choice, and resulting structure are factored into three 
fairly independent processes: an ideational process 
of representing the speaker's experience, an 
interpersonal process of specifying the interaction 
between speaker and hearer (in terms of speech act 
and role assignments), and a textual process of 
enabling the two other ~3rocesses. This is the meta- 
functional factoring; cf. section 5. 
The meta-functional factoring is possible because of the 
notations developed for choice and realization of choice into 
structure as a configuration of functions. Features originating in 
different meta-functions can be used to co,classify a grammatical 
unit and functions from different meta-functions can be conflated 
so that they apply to the same constituent in a structure. 
4 FACTORING INTO CHOICE AND 
REALIZATION 
4.1 The process of choosing 
The separation of statements of grammatical choice alternatives 
from structure specifications allows the grammar to have choice 
as its central organizing principle. The systemic network notation 
has been developed to make statements 0f minimal grammatical 
choice points and statements about the inter-dependencies 
among these choice points possible. The process of choice is 
itself factored into two parts: (i) Grammatical choice: the 
statement of what the grammatical choice points and their 
interdependencies are -- the systemic network notation just 
mentioned -- and (ii) Semantic choice: statements about how to 
select among the options of the grammatical choice points -- a 
chooser semantics. 
4.1.1 Grammatical choice 
Each choice point is represented by a system. A system is a 
disjunction of two or more options (represented by grammatical 
features like Declarative, Past. and Passive). 8 It has an entry 
condition, which is the condition under which the choice is 
available. As long as the condition has not been satisfied, no 
choice can be made. The condition is a Boolean combination of 
features (without negation, though) -- minimally a single feature. 
When the entry condition is satisfied, one of the feature options 
must be chosen. An example of a system is given below in Figure 
1. 
Together the systems of the grammar constitute a network of 
systems: The features that are the output of one system are part 
of the entry conditions of other systems. The network as a whole 
represents the entire scope of the process of grammatical 
selection; the individual systems represent the decomposition of 
this process into minimal choice points. Below. in Figure 2, the 
network fragment for mood is presented; see section 6. 
4.1.2 Semantic choice 
The process of purposefully choosing among the feature options 
of a system is represented by a chooser or choice expert. The 
grammar supplies us with linguistically justified control points, th'e 
8In systemic grammar, a distinction is usually (and always in work by Halliday) 
maintained between features and functions like SUBJECT, ACTOR, and THEME. 
Features are the building blocks of the paradigmatic organization of grammar, i.e, 
of grammar as choice. Functions are the building blocks of the syntagmatic 
organization, i.e.. of grammatical structure. The distinction is not maintained in 
Martin Kay's Functional Unification Grammar (cf. \[Kay 79\]). 
157 
systems. Each system is assigned a chooser, which is a procedure 
composed of one or more steps leading to the determination of 
which grammatical feature to choose. 
Where is the information relevant to the determination of which 
option should be chosen located? As we have seen, in addition to 
the grammar component, our text generation system has a 
knowledge base and a text plan for the text to be generated. 
We can call these components and other possible sources of 
knowledge the environment of the grammar component. It is 
from this environment that a chooser demands the information it 
needs in order to be able to choose one of the features of its 
systems. It demands this information by presenting formal 
inquiries to the environment. 9 An inquiry is asked of one or more 
parameters. The parameters are variables like PROCESS, GOAL, 
TEMPOo, and POLARITY for which conceptual values are identified 
in the generation of every grammatical unit. As we will see 
presently in section 4.2, grammatical structure is a specification of 
grammatical functions and the variables correspond to those 
grammatical functions. The conceptual values are called hubs; 
they are concepts from which other concepts can be accessed. 
For instance, once a concept for a particular action has been 
identified, the participants in the action can be identified through 
the action concept. The inquiries are the only interaction between 
the choosers and the environment. 
4.2 The realization process 
There is a separate notation for the realization process. 
Grammatical structure is defined in terms of relations that can 
hold between grammatical functions; grammatical structure is a 
configuration of functions like SUBJECT, PROCESS, ACTOR, and 
THEME. The relations (conflation, expansion, ordering; see below) 
are introduced by realization statements. In the realization 
process, a function structure is specified step by step: A small 
number of realization operators operate on one grammatical 
function, a combination of grammatical functions, t° or a 
grammatical function and a set of features, tl A realization 
statements consisting of an operator and one or more operands is 
associated with a particular grammatical feature in a system; when 
that feature is chosen, the realization statement can be activated. 
9These formal inquiries have informal versions that are informal questions in 
English used for purposes of discussion and presentation. 
10The realization operations include Insert. which inserts a function into the 
structure being built, Expand, which specifies a constituency relation between a 
function and one or more daughters, Order, which order two grammatical 
functions, and Conflate, which states that two functions, say SUBJECT and AGENT, 
describe the same constituent. Two functions are not ordered until it is clear that 
the ordering imposed is the final one. There is thus no need for movement 
h ~;formations. In fact. there are no transfo rmations at all: A realization is only 
stated at a point where it is clear that it represents the final state. 
11This latteP category of realization operator serves to state how the functionally 
defined constituents of a particular structure, say clause structure or prepositional 
phrase structure, are to be expressed grammatically or lexically. We will meet the 
operator Classify which associates a texical feature with a function; this feature is a 
constraint on what lexecal items can realize the constituent that the function 
defines. 
Among the important properties of the realization process, we 
find: 
• The specification of structural presence (the insertion 
of a function into the structure being built) and the 
specification of constituency relations are separate 
from ordering specifications. For example, the 
specifications of the presence of FINITE, the finite 
verbal element of a clause, and SUBJECT are separate 
from specifications of their ordering. Either can be 
specified to follow the other and there is no need for a 
transformation to invert an original ordering. This 
follows the general tendency in the grammar towards 
factoring the realization (i.e., structure building) 
process into functionally motivated steps. It is typically 
the case that the presence of a function and its 
ordering with respect to other functions serve two 
different purposes• 
• There is a "unification" operator on functions, called 
Conflate, that enables the grammar to reconcile 
function structure fragments that are contributions 
from areas of the grammar serving different purposes. 
For example, SUBJECT is conflated with different 
functions depending on the voice of the clause 
-- ACTOR, GOAL, RECIPIENT, etc.. 
• Collections of features that determine how each 
constituent of e.g. clause structure is further specified 
can be built up step by step. The features are 
associated with functions. Whenever two functions 
are declared to describe the same constituent, i.e., 
are conflated, their feature collections are merged. 
For instance, the auxiliary had has that form in our 
example because it serves both the function TEMPO o 
which constrains it to be a past form and the function 
TEMPO~ which constrains it to be a form of the auxiliary 
have. 
Now I will show in some more detail how the sentence 
generation process is organized. I will use the example already 
introduced and structure the discussion around the meta. 
functional factoring of sentence generation. We will see examples 
of all the characteristics of the choice process and the realization 
process identified above. 
5 META-FUNCTIONAL FACTORING 
To see how the multi-functional factoring works, we will return to 
our CATHEDRAL-BUILDING example and look at it first in an 
interpersonal perspective, then in an ideational perspective, and 
finally in a textual perspective. Different perspectives draw on 
different types of information in the environment. The final 
wording the grammar will give us is Had Sir Christopher Wren 
been going to build a cathedral ever since his youth?. We will 
consider the three meta-functions identified above; each 
corresponds to a different "event". There is the textual event 
itself, the event or process of creating a text for the addressee that 
enables the speaker to achieve his goals (the textual meta- 
function). In addition, we have (i) the speech event, an act of 
158 
speaking involving speaker and addressee (the interpersonal 
meta-function), and (ii) an event in the speaker's experience (real 
or imagined, recalled or projected) (s)he wants to represent (the 
ideational meta.function). 12 
5.1 Interpersonal choices 
When they explore the part of the grammar that deals with the 
clause as interaction between speaker and hearer, choosers ask 
questions that have to do with some aspect of the speech act, 
such as: (i) Mood, i.e., a classification of the speech act: Is the 
speech act (BUILDING.QUESTION) a command? Is the speech act 
a question? I will use the mood area below to show in more detail 
how the grammar works; see section 6. (ii) Identity of 
speaker/hearer: What is the identity of the hearer? Is the hearer 
included in the proposition? Here there is no involvement of 
speaker/hearer. (iii) The polarity of the speech act: Is the speech 
act a positive assertion or a denial? For polarity in our example, 
see section 6.4. (iv) The sincerity of the act: Is the assurance of 
the speaker's sincerity to be expressed? Is a request for the 
bearer's sincerity to be expressed? Here we do not have a 
specification of a marking of sincerity. 
5.2 Ideational choices 
Second, consider the exploration of the clause as a 
representation of our experience. Chooser questions here 
concern the structure and character of the conceptual situation 
we are to represent. (i) Transitivity, i.e., the organization of our 
experience as a process with one or more participants and 
possibly attendant circumstances: Here we choose to represent 
CATHEDRAL-BUILDING as an external process where one entity 
(SIR CHRIS) causes the building process, which effects, i.e., 
brings into existence, another entity (CATHEDRAL). 
The function structure generated by realization statements that 
re-express our choices as structure has as functional constituents 
ACTOR, PRocEss, and GOAL, all of which carry hub associations. 
ACTOR is associated with SIR CHRIS, PROCESS with BUILDING, 
and GOAL with CATHEDRAL. In the final wording of the clause, Sir 
Christopher Wren is the ACTOR of the clause, built the PROCESS, 
~nd this cathedral is the GOAL. 
(ii) Tense, i.e., the organization of our experience in terms of 
time relations: How is the event from our experience (here the 
CATHEDRAL.BUILDING event) to be related temporally to the 
speech event? This intricate question will be further examined in 
section 7 below. 
5.3 Textual choices 
Finally, let us look at the clause as a message, the textual 
perspective. (i) Voice: Of two particular ideationally identified 
12These two events may overlap in various ways. of course, as in so.called 
performative sentences. 
concepts, SIR CHRIS associated with ACTOR and CATHEDRAL 
with GOAL, which is conceptually closer the the topic of the 
paragraph being created? Is the causer of the event to be 
mentioned? In our example, the concept WREN is the paragraph 
topic and we get an active clause with a ¢onflation of ACTOR and 
SUBJECT, i.e., ACTOR/SUBJECT. 
(ii) Theme: For a particular ideational function, we ask if it serve 
as a conceptual context for the rest of the clause? For example, it 
is determined that CATHEDRAL is not to serve this function. 
Similarly, for interpersonal functions. Here, the conceptual context 
in relation to which the remainder is interpreted is FINITE, an 
indication that the clause expresses a question about polarity. 
The different strands of functional reasoning hinted at above are , 
unified into one structure as I will show below in section 8. 
Meanwhile, mood and tense will serve as representatives of the 
full range of choices sketched in this section. 
6 INTERPERSONAL CHOICES: MOOD 
Mood is the interpersonal part of clause grammar that expresses 
the role the speaker adopts and the role (s)he gives to the 
addressee in terms of speech act. I will present the choice 
organization of mood first, then the structural effects of different 
choices, and finally I will show how mood selections can be 
controlled. 
6.1 Mood choices 
In English there is a grammatical choice for clauses between 
imperative ones and indicative ones. This choice of the mood of a 
clause is represented by the mood system; the two options that 
constitute the choice are represented by the features Imperativ~ 
and Indicative. Only clauses with a finite verb select for mood; 
infinitival and gerundial ones do not. This fact is captured through 
the entry condition of the system, which says that if the clause is 
Finite. the mood system can be entered. A diagrammatic 
representation of the system is given in Figure 1. 
Finite 
Indicative 
i Imperative 
KEY TO GRAPHIC NOTATION 
Entry condition: "Finite" 
Feature options: "Indicative" and 
"Indicative" 
Figure 1: The moodsysteminEnglish 
£59 
The feature Indicative is the entry condition to the system of 
IndicativeMood where the options are Declarativ@ and 
Interroaativ¢. There is an additional step. The feature 
Interroaative is the input to the system InterrogativeType where 
the options are Whlnterroaative and Polaritv-lnterroaative. This 
network is represented diagrammatically in Figure 2. The boxes 
under the features in the diagram contain realization statements. 
Our example can be represented as a path through the network 
for mood. The features Indicative, Interroaative, and 
Polaritv-lnterroqativ@ are selected in that order. Each feature has 
structural consequences; the functional structure is built step by 
step. 
6.2 Realizations and the structure of mood 
The structural realization of mood is in the MOO0 constituent, a 
function which embodies the mood or speechact aspect of the 
clause. The internal structure of MOO0 expresses the mood 
selection of the clause. 13 The two principal daughters are 
SUBJECT and FINITE, the finite verbal element of the clause. In 
1 
I 
} 
I 
I 
o 
0 0 
E 
E E 
f- F- 
E 
131ndicative clauses typically have a SUBJECT in English. whereas imperative 
ones do not. Consequently, there is a realization statement which says "insert 
SUBJECT" if the clause is !n,dicativ e. This means that the grammatical function 
SUBJECT iS inserted into the grammatical structure being built. There is no need to 
delete SUBJECT in imperative clauses; the function is never inserted unless it is 
actually expressed. 
Declarativ~ clauses, SUBJECT precedes FINITE; in 
Polaritv-lnterrooative clauses, FINITE precedes SUBJECT, aS in our 
example. 
In our example, the mood structure will be as diagrammed in 
Figure 3. The constituent organization is the result of the 
application of (Expand MOOD SUBJECT) and (Expand MOOD FINITE). 
MOOD 
..................... 
I I FINITE SUBJECT 
Had Sir Christopher 
Figure 3: Mood structure in polarity interrogative 
6.3 Semantic mood choices 
Each system in the mood network is controlled by a chooser. 
For instance, the mood chooser of the mood system in Figure 
1 above, asks questions that identify information about the speech 
act of the clause to be generated. Basically, if the intention is to 
command, the chooser chooses the feature Imoerativ~, otherwise 
the feature Indicative. 
For our mood system the chooser interaction with the 
environment proceeds as follows: 
ENVIRONMENT CHOOSER 
It is not a 
Is the illocutionary point of 
the surface level speech act 
represented by BUILDING-QUESTION 
(MOOD) a command, i.e. a 
request by the speaker of an 
action by the 
hearer? 
command. 
Then Ichoose feature Indicative. 
This is of course an informal dramatized representation of what 
goes on, but the dialogue illustrates the interaction between 
environment and chooser: The chooser presents a inquiry to the 
environment, the environment responds, and the chooser chooses 
a feature in conformity with the response. 
The inquiry above requests a classification of a hub, called 
BUILDING-QUESTION in the example. The BUILDING-QUESTION 
hub is associated with the grammatical (micro-)function MOOD. 
Two additional inquiries establish that BUILDING-QUESTION 
should be expressed by an Interrooative clause and that this is a 
Polaritv-lnterroaative. 
160 
6.4 A note on polarity 
The choice of mood determines how we choose polarity in 
English. In Polarity-interroaativE clauses, the choice between 
Positive, as in Had Sir Christopher Wren been going to build a 
.cathedral, and Neqative., as in Hadn't Sir Christopher Wren been 
going to build a cathedral?, is a choice that has to do with the bias 
in the reader's assumptions about which situation (s)he thinks 
obtains. 
In our example, an unbiased question is intended and Positive is 
chosen. The realization of the choice is that the function FINITE is 
prohibited from being realized by a verb with the feature negative; 
it is outclassified for that feature: (Outclassify FINITE negative). 
We can symbolize this by associating ".negative" with FINITE. 
Notice that this realization constitutes a constraint on how the 
constituent described by FINITE can be expressed. As we will see 
in section 7, other constraints on the constituent come from 
another part of the grammar (the functions TEMPO o and TEMPO~). 
7 IDEATIONAL CHOICES: TENSE 
Independent of and parallel with the grammar of mood is the 
grammar of tense. The two parts of the grammar originate from 
two different meta-functions, the interpersonal one and the 
ideational one. 14 
7.1 Grammar of tense 
In English Indicative (;louses (cf. the previous section), if they are 
non.modal, there is always a specification of at least one relation 
of precedence between two times, one of which is the time of 
speaking. This is the system of primary tense, whose options are 
Pas__jt vs. Present vs. Future.. The realizations of these features are 
stated in terms of the tense function TEMPO 0. If Pa~t is chosen, the 
realization is (Classify TEMPO 0 past); if Future is chosen, the 
realization is (Classify TEMPO o will). In the latter case, TEMPO o iS a 
separate constituent, as in will build; in the former case TEMPO o iS 
fused, i.e. conflated, with whatever verbal function follows to the 
right when Future is chosen -- as in built. In English, the primary 
present tense is morphologically unmarked. 
It is possible to generate a more elaborate temporal verbal 
structure, with more than one tense function: 
TEMPO o TEMPo t TEMPO z 
will have ( jump )ed 
This is possible because the grammar of tense does not just 
contain the system of primary tense, but also, in principle, 
indefinitely many systems of secondary tense (see especially 
14Note, however, that the full resources of tense are only at work in Indicative 
clauses. For example, we cannot (in English) request of an addressee the past 
execution of an action. 
\[Halliday 76b\]). It is possible to iterate over tense options just as it 
is possible to iterate over tense operators in some tense logics. 
(Cf. will have been going to leave and FPFp where p is a 
proposition and F and P are tense operators.) The iteration 
defines tenses of different orders, starting, with first order (or 
primary) tense, then second order tense, third order tense, and so 
on. 
7.2 Tense choosers 
Each selection of Past, Present or Future corresponds to a 
specification of a precedence relation between two times, T x and 
Ty. These times are concepts in Nigel's environment. The task of 
each tense chooser is to establish what the current times to be 
related are, i.e., a current T x and Ty pair, and what relationship 
obtains between them. This exploration proceeds in a step by 
step fashion, guided by the grammar. 
In our example, there are four times: the time of speaking, called 
NOW, a time prior to that which falls within the period of Sir Chris's 
life under discussion, call it MATURE.TIME, a time prior to that 
which falls within the period of his youth, call it YOUTH-TIME, and 
the time of the building of a cathedral, call it BUILDING-TIME. The 
temporal relations are represented in Figure 4. 
~MAI URE_TIN E ~~NOW YOUTH-TIME ~____..~ 
ING-T IME 
Figure 4: Temporal relations 
The tense functions receive hub associations. First, TEMPO o and 
.TEMPO~ are identified as NOW and MATURE-TIME respectively, 
then the following dialogue ensues: 
ENVIRONMENT CHOOSER 
......................................... 
Yes, it does. 
Does MATURE-TIME 
(TEMPO1) precede 
NOW (TEMPO0)? 
Then I choose Past. 
This procedure illustrates the selection of primary or first order 
tense. This type of activity is repeated for the pair MATURE-TIME 
(TEMPO1) and YOUTH-TIME (TEMPO2) where the choice is a secor~d 
order Pa~t and for the pair YOUTH-TIME (TEMPO2) and BUILDING- 
TIME (TEMPO3) where the choice is a third order F~Jture. As a 
result, we get three orders of tense. (i), (ii), and (iii), the 
realizations of which are: 
161 
(i) Pa$1~ (Classify TEMPO 0 past) 
(ii) Pa@~ (Classify TEMPO I have) 
(Classify TEMPO 3 enparticiple) 
(iii) Fui~ure (Classify TEMPO 2 be going) 
(Classify TEMPO 3 to-infinitive) 
To sum up: Both the process of choosing tense and the process 
of specifying a tense structure are factored into steps that 
correspond to minimal temporal relations. The tense functions are 
ordered as a collection of tense functions: the sequence is iconic 
with the order of tense; increase in order of tense corresponds to 
the left to right sequenc e of tense functions. Since there are no 
more tense selections and no voice auxiliary, TEMPO 3 is conflated 
with PROCESS: (Conflate TEMPO 3 PROCESS) is activated. 
8 RECONCILIATION OF THE META- 
FUNCTIONS: STRUCTURAL RESULT 
8.1 Conflation of FINITE and TEMPO o 
The two function structure fragments we have generated are 
(MOOD FINITE SUBJECT) and TEMPOc/TEMPO ~ TEMPO 2 TEMPO 3. 
Typically FINITE and TEMPO o conflate and the two fragments 
combine into the structure in Figure 5. Similarly, as already 
indicated, we have a conflation of TEMPO 3 with PROCESS. The latter 
function is a transitivity function and carries feature information 
about the transitivity type of the verb (i.e, constrains build in 
transitivity), symbolized by the feature transitive. Each one of the 
functions carries constraining feature information. 
As the figure indicates, there are two consequences of the 
conflation of FINITE with TEMPOo: 
1. Feature constraints derived from independent choices 
are merged and co-constrain the final expression. In 
other words, for polarity reasons, had appears as had 
rather than hadn't, and for tense reasons, it appears in 
this form rather than for example has, have, wi//, or 
was. 
2. The final sequence is a result of two independent 
ordering specifications, viz. the mood specification 
that FINITE comes before SUBJECT and the tense 
specification of the ordering of tense auxiliaries. In 
other words, as a tense auxiliary, had precedes been 
going to build, and as the finite element of the clause, 
it precedes the subject. 
8.2 Other contributions to resultant clause structure 
Other aspects of the final structure come from transitivity, voice, 
theme etc. (as we have seen in section 5): 
-From transitivity we get AcToR, PROCESS, and GOAL 
with feature specifications. 
-From voice we get the conflation of SUBJECT with 
ACTOR. 
• From theme we get the conflation of THEME with 
FINITE. 
TO sum up: Depending on the perspective we lay on the clause, 
the phrase Sir Christopher Wren will be SUBJECT (interpersonal 
perspective) or ACTOR (ideational perspective). We say that these 
functions are conflated (symbolized SUBJECT/ACTOR). The 
conflation is the result of bringing independent lines of reasoning 
together. It is an operation that can only be performed on 
functions, not on categories like NP, N, and VP. The resultant 
structure is given in Figure 6 (associated features are left out). 
Note that had, Sir Chris, etc. are not the result of equally many 
functions. Some constituent play a role only in one component 
(e.g. tense: be going) whereas others realized more than one 
function (Sir Chris, for example). 
One important property of these conflations is that they could 
have been otherwise, if the choosers had received different 
responses fromthe environment and thus had made different 
choices. For instance, we could have SUBJECT/GOAL and get the 
clause Had a cathedra/ been going to be built by Sir Christopher 
Wren. Or, with a MODAL displacing TEMPO o in the conflation with 
FINITE: MODAL/FINITE followed by TEMPO c as in may have (instead 
of had). 
FINITE SUBJECT 
-negative 
................................................................ 
TEMPO0/ TEMPO2 TEMPO3 
past be going to-infinitive 
TEMPO1 
have 
................................................................ 
PROCESS 
transitive 
......................... . ........................................ 
had Sir Chris been going to build 
Figure 5: Mood and tense structures combined 
162 
Had Sir Chris I been going J to build I a cathedral 
I I I 
............................................................ 
FINITE I SUBJECT J 
............................................................ 
TEMPO0 I I I I 
TEMPO1 J I TEMPO2 l TEMPO3 I 
J ACTOR I J PROCESS I GOAL 
............................................................ 
THEME I 
............................................................ 
Figure 6: Clause structure 
8.3 A note on the development of the function constituents 
The structure presented above represents clause structure; the 
terminal functions are functions of the clause. It is the solution to 
the problems that the clause has evolved to solve. For the 
development of each constituent, we have to go to go either to 
lexicon or (back) to grammar. The verbal have lexical features 
associated with them and these features serve as constraints on 
what lexical items can be used. The ACTOR constituent and the 
GOAL constituent have to go through another round of 
development in the grammar, in the nominal group part of the 
grammar. Although I have not shown them, features are also 
associated with these two constituents. These features are 
grammatical and will serve as constraints on choices in the 
nominal group part of the network. This process is discussed in 
e.g. \[Matthiessen 83\]. 
9 CONCLUSION 
The first concise presentation of systemic suggestions was 
published when what came to be called ACL was being formed. 
Now, roughly twenty years later, with the first meeting of the 
European chapter of ACL we can look back on substantial 
achievements in both computational linguistics and systemic 
hnguistics, some of them in co-operation. 
However, the most exciting developments are current and 
future. We can see the most ambitious applications of systemic 
linguistics to computational tasks to date. And we can see the 
growing interest in text generation, a task in the context of which 
systemic linguistics seems to have much to offer. 
Here I have.pointed to some properties and designs that come 
from the systemic tradition and which I think are of interest for the 
text generation task. Systemic linguists have done and are still 
doing pioneer work on text organization, turning up insights that 
will most certainly be important to the design of text generators. 
However, here.I have concentrated on contributions in the area of 
grammar and choosers for grammar with a view to showing how 
they help us fulfill the demands place on a grammar in a text 
generator. I have focused on the factoring of the sentence 
generation process that systemic grammar supports. 
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164 
