Topic Maps vs. RDF
Steve Pepper, author of The Tao of Topic Maps (and whose title, incidentally is Information Architect) - makes a concise, interesting comparison of Topic Maps and RDF, arguing for the former. Here's a few points that struck me:
One key difference - I don't know if it is the key difference - is that topic maps take a topic-centric view whereas RDF takes a resource-centric view. That, to me, speaks of the LIS point of view vs. the W3C point of view on these matters, focusing on something that can be indexed vs. something that can have a URI.
Because RDF is fundamentally a "framework for metadata", i.e. for attaching property-value pairs to information resources, it can do the same job as facets. RDF could be used instead of facets, and would arguably provide more power (because of the recursive model and the fact that more metadata semantics, such as datatypes, are pre-defined). But to use RDF instead of facets would mean to lose the connection between the semantic network layer and the metadata, which today is provided for by the fact that facet types and facet value types are topics.
In RDF Schema, RDF has something topic maps don't (yet), that is, a standardized way of expressing an ontology and the constraints upon it...Holger will be going one step further (I believe) with a concrete proposal for a topic map schema language....
Ontopia, of which Pepper is the CEO, has published the The Ontopia Schema Language.