- From: Bijan Parsia <bparsia@cs.manchester.ac.uk>
- Date: Mon, 30 Mar 2009 12:35:08 +0100
- To: public-semweb-lifesci <public-semweb-lifesci@w3.org>
Sad to be drawn in. On 29 Mar 2009, at 17:15, Oliver Ruebenacker wrote: > Hello Matthias, All, > > On Sun, Mar 29, 2009 at 11:13 AM, Matthias Samwald <samwald@gmx.at> > wrote: >> Oliver wrote: >>> As I understand it, an owl:Class is simply something intended to be >>> instantiated. I declare something a class if and only if I intend >>> there to be instances. >> >> This is how you might choose to use OWL, but it is important to >> emphasize >> that many ontologies (including the OBO ontologies and parts of the >> Neurocommons Knowledge Base / Banff HCLS demo) encode a lot of useful >> information just by using classes and property restrictions, without >> instances. > > Isn't that the typical way, that ontologies define classes and > properties and users of these ontologies instantiate these classes? [snip] Nope. It's "a" way, but it's hardly typical and the way you talk about it is seriously misleading. "Instantiating classes" suggests something akin to what one does in an object oriented programming language. I.e., it suggests that individuals are "created" from templates (aka classes). While OWL Classes are used this way in KA systems, it requires careful thought (and the intervention, typically of a "sanctioning" mechanism which indicates which parts of the description are salient for the KA). So, that's just not a helpful way to think about things in the owl context. I myself do use the "TBox=schema; ABox=data" analogy sometimes, but I fear that its utility is limited and risk of misinterpretation very high. Second, there's lots of ways to use ontologies with out having to use logical constants (i.e., individuals). Alignment of database schemas comes to mind. There you might never lift the database data into the ontology, but merely use information from the alignment to rewrite queries. That's not to say that anyone writes class descriptions intending them to be necessarily empty (i.e., unsatisfiable). Just that instance retrieval is one task among many. Cheers, Bijan.
Received on Monday, 30 March 2009 11:35:45 UTC