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Re: Proposal to close ISSUE-83 and ISSUE-8

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Fri, 11 Jan 2008 10:50:38 +0000
Message-Id: <96C87092-0F72-4043-A113-F640F46DF8DD@cs.man.ac.uk>
Cc: "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
To: Jim Hendler <hendler@cs.rpi.edu>

On Jan 11, 2008, at 12:57 AM, Jim Hendler wrote:

> wait, wait - now I'm even more confused than I was -- are we, or  
> are we not, talking about the EasyKeys proposal being part of OWL 1.1?

We are not. It's a separate issue.

> If so, wouldn't the last property in a property chain be  
> implemented exactly the same way?

No. And, also, afaict, ISSUE-8 wasn't requesting "easy property  
chains with a data property at the end" but the general case. For  
easy keys we are proposing a *new syntax*, not just a weaker reading  
of existing syntax. See the proposal:
	http://code.google.com/p/owl1-1/wiki/EasyKeyProposal

> If so, then we aren't closing the issue with a Reject,

I propose we reject it, both in the general and in a hypothetical  
"easy" version. It's hard to see the point of introducing a weaker  
(semantically) form of property chains with the semantics (but  
restricted syntax) of a DL Safe rule.

It might help to read my understanding swrl series:
	http://clarkparsia.com/weblog/category/semweb/rules/swrl/

> if not, then what is the difference?  So couldn't we have  
> "easykeys" at the end of property chains?

I don't know how to make this intelligible. The basic trick of easy  
keys (which have proven to be not trivial to spec out) is that there  
are DL Safe rules which capture a lot of the use cases for keys  
(i.e., key checking in data), so we are going to provide syntactic  
sugar for such rules.

But that doesn't change the nature of the property in other contexts,  
so it doesn't make "key properties" easier in data chains. Indeed, we  
might have to forbid key properties from appearing in class  
expressions to avoid surprising behavior.

>  -JH
> p.s. btw, I did look at Uli's slides, but without the accompanying  
> explanation for the non-theorist, and there was very little in the  
> log, the details were not terribly clear - I was assuming at some  
> point there'd be some description of the solution in one of our  
> documents.  I

(You got cut off.) The short answer is that the proposal to the WG  
has not been yet made. Uli and I were tasked to work on it. We are  
working on it, but there are several tricky areas. (As you might see  
from the google code wiki, we've been working on it for months.) In  
particular, dl safe data property atoms were not really fully speced.  
So we can't just rely on them :( we have to figure out how they  
should and thus will work (e.g., in the RIF version).

Cheers,
Bijan.
Received on Friday, 11 January 2008 10:50:52 GMT

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