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Re: Rich Annotations

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Sun, 25 Nov 2007 04:51:14 -0500 (EST)
Message-Id: <20071125.045114.124055726.pfps@research.bell-labs.com>
To: bparsia@cs.man.ac.uk
Cc: public-owl-wg@w3.org

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Subject: Rich Annotations
Date: Fri, 23 Nov 2007 15:36:55 +0000

> Time to kick off discussion.
> The current draft of the proposal is here:
> 	http://www.w3.org/2007/OWL/wiki/Annotation_System
> If people would like examples "in action" I can easily supply them.
> In the telecon, Jeremy expressed basically two qualms which we can  
> see reiterated:
> 	<http://www.w3.org/mid/4746D424.5060203@hpl.hp.com>[1]
> The qualms are:
> 	1) This is a big change (too big for an OWL 1.1 change)
> 	2) This is hard to deal with in OWL Full

I agree with Jeremy that the overall proposal is quite a major change,
in the basic way OWL works, if not in changes required for tools.

> I don't think it's a big change and I tried to illustrate that with  
> one way of formalizing it (with external documents). A rather simpler  
> way is to add statements to reified annotations (which are already,  
> if very weakly, accounted for).
> There are three aspects of the proposal:
> 	1) Blobs of annotations (mere syntax)

This is a minor change, and one that is very useful.

> 	2) Annotation spaces (an extension of the current "no semantics"  
> interpretation; OWL Full can be handled by taking the union of the  
> spaces).

This is a minor or moderate change to the status of annotations in OWL

> 	3) mustUnderstand (this *is*, perhaps, a major extension, but an  
> extra logical one; it's a very standard bit of webbiness! it's a hook  
> that allows for extensibility).

I view this as a major change.  Through this part of the proposal one
could change the meaning of just about any part of the OWL syntax.  I do
not view this as a good thing.  If one wants extensions to OWL, then why
not build a real extension to OWL?  

(Are there other web proposals that look like this one, by the way?)

> The degree of 3 is *very* minimal. It's basically a flag saying "Hey,  
> the author has done something funky and unless you know what that is  
> you are at high risk of misrepresenting that intent!!!" Thus, it does  
> not *need* a semantic treatment. This captures a *fair* bit of  
> current practice (i.e., where in people extend OWL in a variety of  
> ways, from e-connections to SWRL), but improves interop.

I don't buy this.  How does it improve interoperability?  If a tool sees
one of the "mustUnderstand" things, the tool really can't do anything to
the document.  Worse, because the document would be syntactically
conforming to the OWL spec, sloppy tool writers and users are encouraged
to use the document anyway, leading to incorrect results.  I think that
it is much better to just come out with syntactic extensions

> Indeed, annotation spaces can be seen as syntactic sugar for literals  
> or other encodings of syntax into owl or of using multiple documents.  
> So conceptually (and praxis-wise) there is nothing new except the  
> hint to tools that some encoding might be very significant.

Well, I guess, but, again, I think that the better way to go is to have
a syntactic extension.

> Cheers,
> Bijan.

Peter F. Patel-Schneider
Bell Labs Research
Received on Sunday, 25 November 2007 10:07:11 UTC

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