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Where DAML+OIL deviates from the RDF-Schema spec

From: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
Date: Wed, 28 Feb 2001 11:08:32 +0100
Message-ID: <3A9CCE20.AE4DCB3D@cs.vu.nl>
To: www-rdf-comments@w3.org
The following already appeared on www-rdf-logic,
but I was asked to cross-post here as well.

Frank.van.Harmelen@cs.vu.nl              http://www.cs.vu.nl/~frankh
Department of AI, Faculty of Sciences,  Vrije Universiteit Amsterdam
de Boelelaan 1081a, 1081HV Amsterdam, The Netherlands
tel (+31)-20-444 7731 fax&voicemail (+31)-20-8722806


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As many of you will be aware, DAML+OIL is a web-based ontology-language
built on top of RDF Schema. It is expected to play a role in the new
Semantic Web initiative of the W3C.  (See www-rdf-logic for extensive
discussions on DAML+OIL).

As input to the new RDF Core working group (also under the Semantic Web
initiative), the following is a list how (and why) DAML+OIL
intentionally violates the RDF Schema spec.

They are quotes from the DAML+OIL reference doc at
http://www.daml.org/2000/12/reference.html

[1] "Warning: The RDF Schema specification demands that the
subclass-relation between classes must be acyclic. We believe this to be
too restrictive, since a cycle of subclass relationships provides a
useful way to assert equality between classes. Consequently, DAML+OIL
places no such restriction on the subClassOf relationship between
classes;"

[2] "[in DAML+OIL] multiple domain expressions restrict the domain of P
to the intersection of the class expressions.  Warning: This is contrary
to the semantics of the domain element in the RDF Schema specification,
which we believe to be flawed."

[3] "Warning: Although the RDF Schema specification only allows one
range restriction for each property, it seems quite natural to allow
multiple range restrictions. These would then again be interpreted as
saying that the range of P must be the intersection of all the class
expressions."
Received on Wednesday, 28 February 2001 05:08:36 GMT

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