Techniques are disclosed for textual analysis. In an example, a text analysis application constructs a discourse tree that represents rhetorical relationships between fragments of text. The application matches each fragment that has a verb to a verb signature, thereby creating a communicative discourse tree. The application identifies, in the communicative discourse tree, a terminal node including a nucleus elementary discourse unit, which is dominant to a corresponding satellite elementary discourse unit. The application extracts, from the communicative discourse tree, a particular verb signature corresponding to the nucleus elementary discourse unit. The application determines a subject from the verb signature and forms a question fragment from the subject.