“Systemic Functional Hypertexts”

Alexander Mehler University of Trier mehler@uni-trier.de Rodney Clarke University of Wollongong rclarke@uow.edu.au

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.

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