W3C home > Mailing lists > Public > www-rdf-interest@w3.org > November 2001

RE: RDFS bug "A property can have at most one range property"

From: Peter Crowther <peter.crowther@networkinference.com>
Date: Mon, 19 Nov 2001 11:11:21 -0000
Message-ID: <B6F03FDBA149CA41B6E9EB8A329EB12D1ABC63@vault.melandra.net>
To: "'tarod@softhome.net'" <tarod@softhome.net>
Cc: www-rdf-interest@w3.org
> From: tarod@softhome.net [mailto:tarod@softhome.net]
>   Once again we are talking about vocabularies and different 
> vocabularies for the same rdf, etc...
>   Ok, I want to understand the reason of RDFSchema. RDFSchema 
> is used to define the template (?) you need to follow to write a RDF 
> Document.

Sort-of.  Dan Brickley's email on the subject states the reservations more
clearly than I could.

> So, if
> I write a RDF Schema everybody who write a RDF Document 
> should write it as the Schema specifies.

As a human writer of RDF, you could use RDFS in that way, yes.

> You can define a lot of vocabularies and you can
> rewrite your validation algorithm, so, the validation of a 
> RDF Document
> should be independent of the validation of a DAML Document. 
> You can specify different semantics for both.

Not entirely.  Ideally, DAML would be a strict superset of RDF (and, indeed,
of RDFS).  If this isn't true, and there are RDF semantics that are not
present in DAML, then it's difficult to see why the designers of DAML would
want to use RDF (or RDFS) as a basis.

> If we talk only about RDF and RDF Schema, why
> is better the new approach than the old one?

Because the Semantic Web is a very different environment to a traditional
knowledge- or data-representation system.  It is not possible to control, or
even to discover, who will use, amend or extend your vocabulary.  Therefore,
it is important to create specifications that are well-behaved in such
circumstances.  In the example I gave previously, I argued that an
interpretation as conjunction was 'better-behaved' than an interpretation as
disjunction, because it would be more obvious sooner when there were
problems with combinations of amended and/or extended vocabularies.  As a
developer (of software, of systems or of vocabularies), I'd much rather see
an easy-to-find, large problem that can be solved than a dificult-to-find
intermittent problem that is never really traced successfully.

		- Peter
Received on Monday, 19 November 2001 06:12:45 UTC

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