RE: Intersection of properties?

> What? The argument against boolean role boxes, in general, is that  
> it's relatively hard to do and there's been relatively little demand  
> for it. ALBO is *very* expressive but, you know, doesn't have  
> cardinality restrictions.

> I personally don't feel a burning desire for role conjunction.  
> Perhaps you could list use cases?

I think that it is hard to gauge demand for currently unsupported expressivity in OWL, as there is no "big list" of expressivity features of different languages from which non-logicians could say "hey that would be really useful in OWL". There are clearly a lot of languages available with different expressivities, but because they rarely make it to the tooling stage, unless you know what you are looking for you have to trawl through some quite specific literature.

I for one have often only come to understand new expressivity features in OWL by interacting with it through tools that support them. Once it is there, I can start with trivial examples to satisfy myself that I know what I am really saying and how new statements may interact in complex ways with other statements in my ontology. At that point I can evaluate whether my ontology would benefit from the new statements. For example, when role chains first appeared, I though "eh? How could these be useful?". But now I am finding all sorts of uses for them, but only through experience with them.

There seems to be an underlying expecation in the working group that OWL users will know what expressivity to ask for, and not only that, but they should provide "real" motivating examples to persuade the working group that its worth the effort. This too is a lot of effort on the users part, especially if the end result is just being told that it is not possible for one reason or another. 

Going out on a limb here - and I dont expect this will happen - but I dont see why OWL-Full can't be furnished with the appropriate syntax for *potential* expressivity like role conjunction so that people will a) know what extentions are theoretically possible and therefore be able to ask for them and b) be able to play around with them (albeit only syntactiacally) and generate the kinds of use cases that you and the working group are looking for, possibly even with tool support for the process.

Cheers,
Dr Andrew Gibson
Universiteit van Amsterdam


-----Original Message-----
From: public-owl-dev-request@w3.org on behalf of Bijan Parsia
Sent: Sun 8/3/2008 9:17 PM
To: Jeff Thompson
Cc: Michael Schneider; public-owl-dev@w3.org
Subject: Re: Intersection of properties?
 

On Aug 3, 2008, at 7:58 PM, Jeff Thompson wrote:
[snip]
> I sounds like many implementors

No, it doesn't sound like that. Those were all theory papers.

> see that even OWL 2 is not expressive
> enough to solve their data processing needs, and so everyone has
> their own extensions in Pellet, etc.

? No. The implementation of ALBO is not, by any means, production  
quality (or would purport to be even vaguely scalable to realistic  
kbs). There's only one, sorta implementation of PDL (Peter's DLP,  
which is sorta defunct).

So, I don't know where you're getting this from :)

> And yet, the argument against
> adding more expressiveness to OWL 2 (still decidable) is the fear
> that not enough people will implement it and so that "OWL 2 compliant"
> won't mean much.

What? The argument against boolean role boxes, in general, is that  
it's relatively hard to do and there's been relatively little demand  
for it. ALBO is *very* expressive but, you know, doesn't have  
cardinality restrictions.

I personally don't feel a burning desire for role conjunction.  
Perhaps you could list use cases?

> I know it's a difficult political task to balance.
> Is the general assumption that there will need to be several more
> revision cycles to OWL before a large number of people will use it
> as specified without needing to add their own incompatible extensions?

I think you're confused. OWL already is used by a large number of  
people without needing to add their own incompatible extensions. If  
you have a strong need for very expressive role boxes, I suggest you  
submit a paper to OWLED detailing your needs.

Cheers,
Bijan.