- From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
- Date: Fri, 07 Feb 2003 09:51:02 +0000
- To: www-webont-wg@w3.org
I presented the current docs to an HP group, and was unable to explain why
the following RDF vocabulary is omitted from OWL Lite, for use with data:
Classes:
rdf:Bag
rdf:Seq
rdf:Alt
rdf:List
Properties:
rdf:_NNN
rdfs:member
rdf:first
rdf:rest
Other:
rdf:nil
As far as I can see there is no reason (other than aesthetics), although
incorporating rdf:_NNN and rdfs:member would involve only supporting their
use as ObjectProperty. Mixed usage, in which rdf containers are used with
both resource and literal values only fits in OWL Full.
The use of rdf:first and rdf:rest as part of the syntax for OWL does not
interact with their use as
rdf:value *does* seem technically problematic, as well as unaesthetic,
because it is primarily used with string values, but may be used with
resource values.
These could be added to OWL Lite, by treating the classes above as
owl:Classes, the properties above as owl:ObjectProperties and rdf:nil as
an owl:Thing.
Moreover, rdf:first and rdf:rest can be treated as owl:FunctionalProperty,
with domain rdf:List and the range of rdf:rest can be constrained to
rdf:List union { rdf:nil }.
============
Moreover, I believe the current rationale for the existence of owl:Class as
a distinct concept from rdfs:Class is flawed.
In OWL Full they are the same concept.
In OWL Lite and OWL DL any of the statements that might reveal differences
between the concepts are syntactically excised. Hence the justification
based on rdfs:Class including members such as owl:FunctionalProperty,
whereas owl:Class does not is spurious.
It would be simpler to just use rdfs:Class throughout, and nothing would
break. (The correspondence theorem may need additional care).
Jeremy
Received on Friday, 7 February 2003 04:51:20 UTC