Re: Playing with sets in OWL...

On Sep 8, 2006, at 11:39 PM, William Bug wrote:

> 	3) Re:anonymous classes/individuals of the type Alan describes:   
> These are essentially "blank nodes" in the RDF sense - "unnamed"  
> nodes based on a collection of necessary restrictions, if I  
> understand things correctly.  Please pardon the naive question, but  
> aren't there some caveats in terms of processing very large RDF and/ 
> or OWL graphs containing "blank" or "anonymous" nodes.  For many  
> OWL ontologies, this might not be a concern, but if one were to be  
> tempted to express a large variety of such sets based on different  
> groupings of the sequence probes on a collection of arrays -  
> groupings relevant to specific types of analysis - I could see how  
> these anonymous entities - especially the anonymous sets of  
> individuals - could really proliferate.

Predicting the performance of even small OWL ontologies is a bit of a  
crap shoot at the moment, it appears, though there is ongoing  
research to try to address this. In cases I've worked on I've had  
really small ontologies blow up, and larger cases run extremely  
quickly after some solicitation of advise from the DL experts and a  
little experimentation.

I think the best thing in these cases are to try to represent what is  
desired, see what happens, and ask for help when it doesn't scale as  
desired. Such cases will, at the minimum be grist for future  
research, and I get the sense that they are highly valued by OWL  
researchers.

Although I used an anonymous individual in one of the examples, there  
is really no need to, and in fact my recommendation would be to avoid  
their use by generating a name in those cases, taken from a namespace  
that is advertised to be unresolvable and used for this purpose. This  
not for reasons of efficiency as much as for understandability - the  
anonymous nodes are properly considered existential variables and  
should probably be used when you know that's what you want.

-Alan

Received on Monday, 11 September 2006 23:35:38 UTC