Systemic Functional Hypertexts

Systemic Functional Hypertexts

Alexander
Mehler

University of Trier
mehler@uni-trier.de

Rodney
Clarke

University of Wollongong
rclarke@uow.edu.au

2002

University of Tübingen

Tübingen

ALLC/ACH 2002

editor

Harald
Fuchs

encoder

Sara
A.
Schmidt

Although texts exist in social contexts, models of hypertext authoring
generally exclude this aspect of the structure and function of texts.
Readers and writers require situational and cultural contexts in order to
understand the meanings negotiated in texts. These contexts are generally
ignored because of the lack of any language model underlying hypertext
authoring or the models used do not reflect relationships between text and
context. In this paper we describe how Systemic Functional Linguistics can
be used to create Systemic Functional Hypertexts
(SFHT), which includes many aspects omitted from conventional models: (i)
text forming resources, (ii) intra- and intertextual relations occurring
within their (iii) situational and cultural contexts. SFHTs are described
with the help of the unified modeling language.

1 Introduction
According to Systemic Functional Linguistics (SFL; Halliday 1978; Martin
1992) texts are produced/received as functional units in patterns of
wordings and grammar dependent on social context. Within SFL, 'context' is
theorized using a bistratal organization of genre and register: whereas
registers manifest variety according to situational use, genres correspond
to the staging of social processes as part of the context of culture. It is
a fundamental insight of SFL that the constitutive dependence of text on
context is bilateral. That is registers (genres) are not only instantiated,
but also constituted by means of texts. This relation of mutual dependence
can be observed on the basis of covariation of
textual and contextual features (Lemke 1995). According to this view,
changes in context are correlated with changes in texture (i.e.
lexico-grammatical choices). Thus, covariation can be used as a source for
predicting intertextual relations: the more similar two registers (genres),
the stronger their dependence, the higher the probability that their textual
realizations are intertextually related.
From this perspective, hypertext authoring becomes crucial in the sense that
it has to reflect the contextsensitivity of intertextual relations in order
to offer their readers value-added information. The perspective of
traditional two-level-hypertext systems (Mayfield 1997) does not suffice,
since it only formally distinguishes representational formats for the
derivation of links and their presentation without taking context layers
into account. What is needed is a system which does not only allow to model
thematic progression (Kuhlen 1991), and adaptivity to varying situational, user centered
views (Kuhlen 1994), but also genres and registers and
their covariation with texture. In the following, the integration
of these perspectives (i.e. hypertextual superstructures and
contextsensitivity) on the basis of SFL is described using the concept of
systemic functional hypertext.

2 Systemic Functional Hypertexts
Applying SFL to hypertext relates to the question of how
to specify which links of which textual units on the background of which
linguistic and social semiotic entities. In order to approximate
an answer, the concept of Systemic Functional
Hypertext (SFHT) is introduced as an n-level hypertext system
which includes at least a genre layer (for
modeling genres, their constituents and staging), a register layer (for modeling registers, their constituents and
accessibility constraints), a texture layer (for
modeling types of texture forming resources, their syntagmatic and
paradigmatic dependencies and linguistic realizations patterns), and a text layer (for modeling intertextual relations of
texts as links in hypertext). Whereas the first three layers describe
different resources for text linkage, the last layer deals with the
organization of concrete links.

2.1 Systemic Functional Links
In SFHT the concept of a link is concretized in two respects: (i) links
are introduced as a kind of sign. (ii) This
allows to ask for the role of links in the superisation (i.e. constitution) of higher level signs and
their communicative function. To be more
concrete: whereas the expression plane of a
systemic functional link (SFLink) is
given by its surface structural manifestation by means of anchor,
reference, and referent, its content plane
is determined by the intertextual relations it expresses. Since these
relations are seen to co-vary with relations of genres and registers
contextualizing social (communicative) processes, the view of SFLinks as
being signs allows to introduce the concept of function in hypertext. To take a step forward in specifying
SFLinks, two dimensions are distinguished:
1. Foundation: does a link
manifest linguistic cohesion or
situational and generic
coherence of textual reference and referent?
2. Structure formation: does a
link associate pairs of texts or
does it participate in chains of
interlinked texts as manifestations of systemic functional
progressions?

Based on these criteria, several types of links can be distinguished: At
the lower end purely associative, context-insensitive links are
distinguished-the typical case of links produced in the area of
automatic hypertext authoring (Salton et al. 1993). The construction of
lexically cohesive as well as path sensitive links has an intermediary
status. More coherent links are produced if context layers are taken
into account. Thus, on the upper end of the matrix situational as well
as generic coherent, contextsensitive paths of interlinked texts which
serve to manifest systemic functional progressions are
distinguished.
The systemic functional perspective chosen to reconstruct the concept of
hypertext allows to reflect the specific complexity of signs. Instead of
describing SFHT by means of contextfree rule systems, contextsensitivity
is taken as the starting point. Following this premise, several moments
of informational uncertainty can be distinguished as necessary
conditions for the functional impact of SFHT: (i) Contextsensitivity: the same link may have multiple
linguistic, situational and generic sources (polymorphism). (ii) Polyfunctionality: the same link may be used
to link different contextual units. (iii) Vagueness: the source of a link may be vague, dissonant,
fuzzy, etc. (iv) Ambiguity: the same
reference can be linked with different referents. (v) Dynamics: links may disappear, emerge or
modify as the text base grows. These moments of complexity correlate
with the constitution of social semiotic entities on the background of
emerging/disappearing usage regularities of signs. SFHTs serve to make
explicit this co-variation of linguistic and
social semiotic system.

3 Conceptual Modeling
In order to make hypertext more sensitive to the situational and cultural
context the operationalization of the concept of SFHT is needed. Beyond
formalization it is conceptual modeling which
precedes their algorithmization and implementation. This paper presents a
conceptual model of SFHT using the unified modeling language (UML). Besides
structural aspects including the enumeration and specification of
constituents of the linguistic and social system, dynamic aspects of SFHT
are modeled, too. Structural building blocks of SFHTs including genres,
registers, texture forming resources, intratextual/intertextual relations,
systemic functional progressions, links and paths are interrelated.
Furthermore, co-variation and co-evolvement of text and context are
described as procedural building blocks. The conceptual model is used as a
starting point for the specification of data structures and algorithms for
the computer-based implementation of SFHT systems.

4 Conclusion
This paper applies SFL to the area of hypertext authoring based on the
manifold covariation of social and linguistic system, which allows the same
text to be embedded into different contexts and thus to have different
functions. In order to reflect this moment of polymorphism and
polyfunctionality, the concept of SFHT and their main building blocks are
described. On this background, three principal conclusions can be drawn:
1. Because of the dependence of human information processing on
varying cognitive, situational, and social contexts, a given text
corpus does not have a static, predefined hypertext structure. Thus,
text conversion demands a fundamental reconstruction of the concept
of hypertext from the perspective of a sociosemiotic theory of
discourse which views this dynamics as a precondition for
(hyper-)texts to be functional.
2. This reconstruction is necessarily interdisciplinary in the
sense that it includes insights from semiotics, linguistics and
social as well as computer science.
3. The concept of SFHT, used to formally manifest this
reconstruction, demands a stepwise operationalizing in order to
prepare its implementation. For this sake, UML is used, since it
allows to model structural and procedural aspects of SFHTs.

Thus, this paper contributes to the reconstruction of hypertext from a
semiotic point of view, or more concretely: from the perspective of
computational semiotics.

Bibliography

M.
A.
K.
Halliday

Language as Social Semiotic

London
Edward Arnold Publishers
1978

R.
Kuhlen

Hypertext: ein nichtlineares Medium zwischen Buch und Wissensbank

Berlin
Springer
1991

R.
Kuhlen
Annäherung an Informationsutopien über offene Hypertextsysteme

R.
Wille

M.
Zickwolff

Begriffliche Wissensverarbeitung: Grundlagen und Aufgaben

Mannheim [u.a.]
Bibliographisches Institut
1994
191-224

J.
L.Lemke
Intertextuality and Text Semantics

P.
H.
Fries

M.
Gregory

Discourse in Society: Systemic Functional Perspectives

Norwood
Ablex Publishing
1995

J.
R.
Martin

English Text. System and Structure

Philadelphia
John Benjamins
1992

J.
Mayfield
Two-Level Models of Hypertext

C.
Nicholas

J.
Mayfield

Intelligent Hypertext: Advanced Techniques for the World Wide Web

Berlin
Springer
1997
90-108

G.
Salton
J.
Allan
C.
Buckley
Approaches to Passage Retrieval in Full Text Information Systems

ACM-SIGIR '93

1993
49-58