W3C home > Mailing lists > Public > public-owl-wg@w3.org > November 2007

Re: Rich Annotations Use Cases

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Wed, 7 Nov 2007 17:37:35 +0000
Message-Id: <55E7F2A0-28B5-4644-AE61-BC1737639165@cs.man.ac.uk>
Cc: public-owl-wg@w3.org
To: Alan Ruttenberg <alanruttenberg@gmail.com>

On 7 Nov 2007, at 17:25, Alan Ruttenberg wrote:

> On Oct 31, 2007, at 9:01 AM, Bijan Parsia wrote:
>
>> 3) Language extensions with "must understand".
>>
>> In C&P's implementation of probabilisitc extensions to OWL based  
>> on the P-SHOQ formalism,
>>
>> 	<http://clarkparsia.com/weblog/category/semweb/probabilistic- 
>> reasoning/>
>>
>> we used axiom annotations to turn subclass axioms into conditional  
>> constraints (for example). A system cannot *correctly* ignore  
>> those annotations, but it was a very convenient way to extend the  
>> language (although one could argue that it was potentially  
>> misleading): We didn't have to change any basic parsers or  
>> editors; it worked in all syntaxes for free, etc.
>>
>> In general, better support for extensions is helpful.
>
> I'm a little worried about this, one, in the sense that the file  
> advertises itself as OWL, but really isn't (it has different  
> semantics).

Well, that's what you get from extending the language. From a Protege  
POV (the editor) this is fine. From the reasoner POV, it isn't. The  
mustUnderstand clearly indicates that Protege can hack it but FaCT++  
can't.

This is a pretty standard extensibility mechanism.

> I'd worry that we would arrive at a situation in which there were  
> all sorts of little "must understand" bits from different people,  
> leading to one of two situations - either all should be rejected by  
> reasoners, or the "what the heck, it's just a couple of axioms,  
> let's ignore it".

Care is needed, but this way at least some tools can do something  
sensible.

> Would an alternative to define a different sort of file that has a  
> way of embedding OWL, and then teach tools to use those files too?

Six of one, half a dozen of the other, AFAICT.

And then protege wouldn't work so well with the new files. Shrug.

Cheers,
Bijan.
Received on Wednesday, 7 November 2007 17:36:10 GMT

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