Communicative structure of the sentence refers to the way the speaker structures the information, the way he identifies the relative importance of utterance parts. Usually the utterance consists of 2 parts:
- the topic of discussion: something about which a statement is made (theme = topic)
- the new information, which adds most to the process of communication (rheme = comment).
Some sentences contain only the rheme, they are monorhematic: It is getting dark. In the majority of sentences the constituents are either rhematic or thematic. There are also transitional elements. Sentences containing the theme and the rheme are called dirhematic.
Thematic elements are indicated by the definite article, loose parenthesis, detached parts of the sentence; rhematic elements - by the indefinite article, particles, negations, emphatic constructions. But in the majority of sentences the rheme is also placed at the end, which is achieved by changing the syntactic structure of the sentence.
Means of preserving the progressive information structure:
1) passive transformations,
2) the use of conversives,
3) the use of the personal subject and the nominal predicate.
Means of making the subject rhematic:
1) the constructions there is/there are, it is necessary,
2) inversion.
Thematic elements contribute little to the meaning of the utterance as they reflect what has already been communicated: they have the lowest degree of communicative dynamism (CD). Rhematic elements, containing new information which advances the communicative process have the highest degree of CD.