Recent linguistic trends stress the necessity to investigate not only the system of language, but also discourse patterns. In this context it is important to understand the sentence both semantically and syntactically not just as an “assertion”, being the linguistic counterpart of a fact’, but rather as a component part of a discourse, which in the general case is not a monologue (Hoepelman & van Hoof 1988: 250). The sentence structure should then be described in such a way that its properties imposed by the sentence's functioning in communication are not neglected. This means above all that one must not neglect the topic-focus articulation (TFA), which is one of the hierarchies constituting the syntactic pattern of the sentence, and which exists due to the impact of the communicative function on the structure of language. The results of empirical research continuing the tradition of the Prague School and taking into account the methodological requirements of formal linguistics have made it possible to state that TFA (being not only pragmatically, but also semantically relevant; see Section I below) can be described in an economical way as one of the aspects of underlying structure (or of sentence meaning, of tectogrammatics), and that this hierarchy has its counterparts (means of expression) on the other levels (see Section 2). The importance of the phenomena now subsumed under TFA has been known since Weil (1844). Between the I860s and 1920s, linguists such as G. von der Gabelentz, H. Paul, P. Wegener, A. Marty, H. Amman and O. Jespersen introduced ‘psychological subject and predicate’ (or ‘theme and rheme’, later ‘topic and comment’) into the analysis of general properties of language, and discussed stress and word order as the means of expression of this dichotomy. In Prague, Mathesius I1929, 1939) formulated a linguistic account of the dichotomy from the viewpoint of a structural comparison of Czech (with its ‘free’ word order) and English, pointing out that the subject typically expresses topic in English (whereas its primary function in Czech is being the Actor). Among his followers, Firbas (I957, 1975) analysed the interplay of this ‘functional sentence perspective’ and word order, showing that not only a dichotomy, but a whole scale of ‘communicative dynamism’ is present. After Halliday (I967) brought TFA nearer to the centre of attention of the English-speaking linguistic world, the relevant issues started to be studied also in the context of generative linguistics; see Chomsky (I97I), more recently Jacobs (1983) and Rochemont (I986). However, not much continuity with continental research has been kept within this trend, so that even in the rare cases in which TFA is given due attention, the approaches used for its analysis do not yield a possibility to describe adequately its position in the system of language (see esp. Koktov´, I988a,