Describes four waves of Ranganathan's dynamic theory of classification. Outlines components that distinguish each wave, and porposes ways in which this understanding can inform systems design in the contemporary environment, particularly with regard to interoperability and scheme versioning. Ends with an appeal to better understanding the relationship between structure and semantics in faceted classification schemes and similar indexing languages.
IntroductionThe increasing popularity of tagging, ontology engineering, and information architecture has brought the concepts of classification theory into the zeitgeist of organizational management, science, and business. A popular press example, a book by David Weinberger, draws a caricature of Shiyali Ramamrita Ranganathan as a disciple to mystics and an overly-meticulous traveler (Weinberger, 2007, 85). Although some teachers laud Weinberger's description of facets, it seems that he fails to comprehend the full host of Ranganathan's theories and how they are relevant to developing and evaluating information systems today.Through his long and prolific career S. R. Ranganathan worked toward a coherent and robust theory of classification -a Dynamic Classification Theory. In working toward this goal he developed four successive waves of classification theory. They were: Faceted, AnalyticoSynthetic, Depth, and Abstract Classification (FASDA together) (Ranganathan, 1967;1953). These, listed in roughly chronological order, represent the advancement of his thinking, along with that of his close circle of collaborators and students. We can distinguish between waves by the various layers Ranganathan added to the act of classification. In turn, we see these layers by understanding the components of his complex and ever-evolving theory. Facets constitute but one of those components. Facets, when layered with other components discussed from 1930s to the 1950s form the wave of Faceted Classification.Faceted Classification is a method of breaking the universe of subjects apart into facets. Faceted Classification was based on canons, many adapted from Sayers's work, but Ranganathan expanded and refined them. However, he saw its shortcomings. Where Faceted Classification was rigid, Analytico-Synthetic Classification, the second wave, was more flexible and provided a number of techniques that allowed the classifier more expressive power. We can mark the birth of Analytico-Synthetic classification with a paper in 1950 (Ranganathan 1951). Depth Classification was an offshoot of, yet contemporaneous to, the former, focused on domains requiring richer expressive classificatory power. I place its formal genesis in 1953 with the conference on Depth Classification and Reference Service (Ranganathan 1953). Finally, Abstract Classification, the last wave Ranganathan introduced, was seen as a method whereby classification research could create models of classification. Building on proceeding research, Abstract Classification could generalize from practice, create models of how class...