RE: OWL vs RDF

[Mork, Peter D.S.]

I think that even if you are talking about ontology construction, in most cases you need OWL.  It is certain that multiple overlapping ontological structures will be developed.  For example, in BIRN, there is a core ontology describing neuron-anatomical structures.  However, each brain atlas introduces its own set of structures (based, in part, on the available resolution).  One could try to merge these into a single ontology, but that would be poor engineering.  Instead, a new set of axioms can be constructed that define atlas structures in terms of the core BIRN ontology (and vice versa).  This articulation requires class constructors and equivalence relationships.  Moreover, if the source structures are expressed using DL definitions, the inference engine will often be able to identify additional articulation conclusions.   Peter Mork   As Phil implies below, if you really just need a formalism for nodes and edges, you don't NEED OWL - in fact, for many types of graphs, you don't need RDF.  On the other hand, if you are clearly going to require a formalism with considerable ontological expressivity, you probably want to give the OWL dialects (and their underlying DLs and the toolsets such as ProtegeOWL  and the Pellet, FACT++, and other reasoners, etc.) serious and in depth consideration.   Just to be clear, I'm talking here about ontology construction which I consider just a portion of the required task of semantically formal data representation.  For much of the semantic representation we need to do in large scale biological data repositories, RDF alone will clearly be a sufficient first step, so long as we continue to develop effective means of expressing the triplets in the context of the ontologies and extending the ontologies via analysis (as automatic as is feasible) of the triplet repositories.   Cheers, Bill