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Re: AS&S and WG consensus (was Re: abstract syntax and RDFS)

From: Jonathan Borden <jonathan@openhealth.org>
Date: Thu, 23 Jan 2003 22:04:29 -0500
Message-ID: <0a4901c2c355$51542260$7c01a8c0@ne.mediaone.net>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, <www-webont-wg@w3.org>


Jeremy Carroll wrote:

>
> I had deliberately decided not to offer any reasons, since, as far as I
can
> see, such discussion is out of order - it is about topics that have never
> been raised as issues.

Yes, well I've been disappointed that we often spend far more time
discussing process than actual technical issues.

>
> However, since you ask -
>
> I hope that semantic web users will be able to migrate from RDF thru RDFS
> thru OWL Lite thru OWL DL thru OWL Full - possibly stopping off where
their
> needs are met; possibly skipping a stage if they have specific needs that
> are only met at higher levels.

This is an interesting (and not unexpected) position, which highlights a
fundamental problem with our arrangement of languages.

There is the (mis)conception that RDFS is simpler than OWL Lite which is
simpler than OWL DL which is simpler than OWL Full, yet 'simpler' exactly
how? Cognitively? For implementation?

In terms of "contraints on the language" might we say that RDFS is the least
constrained, followed by OWL Full, then OWL DL and then OWL Lite?

I can see why Peter might make certain decisions based upon this latter
view, whereas you have certain objections based upon a different (former?)
view.

We all must agree that the semantic layering is a compromise and one that
has left certain questions unanswered -- can we implement a complete OWL
full reasoner? etc. So how we organize the 4 languages in a line depends on
our differing priorities. These are issues we need to plainly discuss.

>
> Simply dropping things from the RDFS and RDF vocabulary, apparantly on an
> editorial whim, does not involve any sort of "case".
>
> So I can't live with OWL Lite prohibiting rdfs:seeAlso and
rdfs:isDefinedBy
> because of the additional migration cost for users moving from RDFS to OWL
> Lite. I offer no other defense of these properties - I am not sure that
> there is much of one (I agree with your "wishy washy").

Yes, well, to speak plainly, I expect that if you we forbidden to use the
terms "rdfs:seeAlso" and "rdfs:isDefinedBy" under penalty of death, that you
would be able to design a long and productive life for yourself. Let's not
use the term "can't live with" too lightly, eh?

>
> In summary, it is important to me that the migration path works, which
means
> that RDF and RDFS features should not be arbitrarily dropped from OWL
Lite.

Interesting position -- I really (really) wonder what the role of 'vanilla'
RDFS will be. Instead I'd hope the migration path  might be: OWL Lite -> OWL
DL -> OWL Full. Given OWL, what does RDFS add to the picture -- is it easier
to implement? is it more powerful? is it really easier to learn (given real
world ontological or modelling problems)?

Jonathan
Received on Thursday, 23 January 2003 22:27:56 GMT

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