Given these problems, Systemic Functional Grammar (SFG) has two particular attractions. First, unlike some other theories, SFG emphasises the wider range of factors (semantic, pragmatic, discourse...) discussed in [Tsujii 1986]. More specifically, semantic factors are handled in the ideational metafunction, pragmatic factors in the interpersonal metafunction, and discourse factors in the textual metafunction (see Section 1.2.3). Second, again unlike other theories, SFG is directly orientated towards the explicit organization of the functional choices needed to decide the values of these factors.
The general aim of this thesis is therefore to investigate SFG and its use in English and multilingual generation, and to consider its relevance to the problems of Japanese-English and Japanese-European MT. The more specific aim is to show that SFG offers an approach to solutions for all three of the above problems, as follows.
By traversing a systemic grammar network (Section 1.2.1) from left to right, using an ``inquiry semantics'' approach (Section 2.2.2) to the choices in each system, a set of values of various factors (semantic, pragmatic, discourse...) is selected. The realization rules (Section 1.2.2) for the selected values then generate the structures and words of the output sentence. So a systemic grammar network defines a set of factors of various aspects of meaning which collectively determine the surface structure of target language texts. The realization rules define a method for generating the specific target language text determined by a given set of values of these factors. The inquiry semantics interface defines the inquiries which need to be raised to obtain all (and only) the information needed to decide the values of these factors. In relation to the three problems enumerated above:
This correspondence between the SFG approach to generation and Tsujii's proposed approach to MT was the motivation for the further investigation of SFG and for the development of the cross-linguistic demonstration prototype, which form the contents of this thesis.