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Re: perspectives on OWL v.next and RDF

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Sat, 18 Nov 2006 02:21:42 +0000
Message-Id: <92CB4B53-0F74-419F-9BE5-33289BB53802@cs.man.ac.uk>
Cc: Dan Connolly <connolly@w3.org>, public-owl-dev@w3.org
To: Jim Hendler <hendler@cs.umd.edu>

[Won't get caught up today :)]
On Nov 13, 2006, at 8:54 PM, Jim Hendler wrote:
[snip]
> Bijan - in the interest of bringing things to the mailing lists  
> instead of blog wars (which actually seem to have better Google  
> karma, but never mind) - you put the following as deliverables for  
> a potential WG
>
> Deliverables
>
>     * Syntax and Semantics (S&S)
>     * Outreach material
>           o update/diff//what the wg decides
>           o New material (e.g., tractable fragments)
>     * Test Suite
>
> this reveals one difference - I am not interested in elucidating  
> the many tractable fragments,

That document tried to capture all those "of interest", that is,  
those which we knew had implementations and user communities and  
seemed to have "naturally useful" expressivity. You might notice that  
we did not include any of the "classic" tractable DLs like FL0 or  
even Classic, for exactly these reasons. (Classic might be  
interesting, but my impression is that Classic users mostly migrated  
to more expressive logics, rather than staying in Classic. Or, now  
that I think about it, EL++ might capture a heck of a lot of classic  
uses.)

> that's not a WG activity in my opinion

Really? That seems a bit strong. I don't see why having a spread of  
interesting fragments, if they can attract markets, is not a WG  
activity. I would like to name them, and use the "species" framework  
that WebOnt set up to help guide users.

> - I'd be interested in identifying one particular tractable  
> fragment, naming it, and getting it into note or rec form

I don't see why just one if there are others vendors are willing to  
support directly. There is already an EL++ vendor (Arity something?  
they were at ISWC) and a hornSHIQ and DLP vendor. I think DL Lite  
will have some commercial activity soon. The nice thing is that these  
are all OWL! So let's call them OWL! I think there's a lot of room  
here and that people will use these fragments.

What I would expect the working group to do is examine things like  
the tractable fragments document and your document and others,  
solicit comment, and define a useful and rational subset that was  
helpful to the community.

I think there is room for more fine grained identification: the  
expressivity checker in Swoop is a much loved feature in my  
experience. But *that* seems outside the scope of a WG since there's  
nothing really to standardize and no reason to standardize it. (I  
guess we could give URIs to everything, but that's not so hard nor  
particularly helpful.) However, identifying subsets that are useful,  
easier to use, amenable to scaling or to certain implementation  
techniques *is* useful, because they can help users and vendors "meet  
up".

> to show where we are at the moment - the attached (HTML table)  
> reflects where some of us have been playing - comments welcome

Quick comment, I notice that the chart says that OWL Lite lacks  
complementOf and disjointWith...that's only true syntactically, not  
semantically (one of its problems).  Experience with other tractable  
fragments shows that "disjointWith" is much safer than  
"complementOf". I'd look at DLP or hornSHIQ. I'll point out that DL  
Lite has undergone some evolution...see the paper at OWLED.

Cheers,
Bijan.
Received on Saturday, 18 November 2006 02:22:12 GMT

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