Topical Progessions
The sequences of sentences, Witte (1983a: 319) writes, advance the "discourse topic by developing a succession of sentence topics, sequences that Lautamatti calls topical progressions," which help describe how individual sentences cohere locally and how all sentences within a text cohere globally. Connor (1996) shows that coherence can be mapped using a system of three distinct progressions:
  1. parallel progression, in which topics of successive sentences are the same, producing a repetition of topic that reinforces the idea for the reader (<a, b>, <a, c>, <a, d>);
  2. sequential progression, in which topics of successive sentences are always different, as the comment of one sentence becomes, or is used to derive, the topic of the next (<a, b>, <b, c>, <c, d>); and
  3. extended parallel progression, in which the first and the last topics of a piece of text are the same but are interrupted with some sequential progression (<a, b>, <b, c>, <a, d>).
The relationship between the progression of sentence topics and the semantic hierarchy of a text is captured in Lautamatti's notion of topical depth. Lautamatti maintains that the sentence topic stated first in an extended text is frequently at the highest level in the semantic hierarchy. Lautamatti combines the concepts of topical progression and topical depth to represent a text's topical structure in a topical structure analysis.