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Re: RDF & Trust & OWL & Layering

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 28 Oct 2002 15:25:29 -0500 (EST)
Message-Id: <20021028.152529.01821414.pfps@research.bell-labs.com>
To: sandro@w3.org
Cc: www-rdf-interest@w3.org

From: Sandro Hawke <sandro@w3.org>
Subject: RDF & Trust & OWL & Layering (was Re: Meaning of URIRefs)
Date: Mon, 28 Oct 2002 14:16:00 -0500


> 2) OWL is a different language from RDF only in the sense that English
> using the word "Aardvark" is a different language from English which
> does not use the word "Aardvark".  OWL offers precise definitions of
> some few-dozen "words" which allow people to say things in RDF which
> they could not say otherwise, unless they defined some of their own
> words.

Well, this is only true to some extent, and only because a number of people
have sweated blood to determine a complex, error-prone, and limited way to
make it so.   

> I meant to jump on this earlier, when you said that OWL and DAML were
> "other KR languages [not RDF]".[1]  I can see why you might call them
> different languages (natural language using technical jargon is kind
> of another language), but that's also misleading.

I do not think that it is misleading at all.  OWL and DAML (and any
hypothetical first-order Semantic Web language) knowledge bases should not
be thought of as collections of n-triples.  Instead such knowledge bases
should be thought of as written in some other syntax---one that would be
much more natural for the job.

> ...
> The vision of RDF is that it's another solid step up the semantic
> ladder, where bits and ascii/unicode are lower steps.  (Some people
> put XML as a step here; I think it's just a step sideways.)  This step
> puts us at the semantic Web.  At this step we have one single approach
> to structuring (triples, binary relations), and one form of naming
> (URI-Refs) [plus literals, but they're 90% carbohydrates].  Every
> additional feature you might want to add, like the features of RDFS,
> OWL, DAML+OIL, DC, CC, RSS, etc, is added by picking some identifiers
> and fixing their meaning.

It is precisely this triples-as-king view that is making it extraordinarily
difficult to design OWL, and is making an integrated view of the Semantic
Web layers difficult to produce.  For example, how can you define
first-order quantification, or even disjunction, in this manner?


Peter F. Patel-Schneider
Bell Labs Research
Received on Monday, 28 October 2002 15:25:39 UTC

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