Introduces this special issue which describes several approaches to semantic knowledge representations. Discusses the various quantitative procedures employed in the articles, noting that they can also serve as theoretical approaches to knowledge representation. (SR)

Comments on a set of five analyses that all examine the same data (the discourse of a problem-based learning group in medicine). Argues that each of the analyses is representative not only of a research tradition, but also of a distinct research language and, as such, can be analyzed on the basis of the expressive potential of that language. (SR)