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Some comments on RDF Schema as RDF/XML

From: Qu Yuzhong <yzqu@seu.edu.cn>
Date: Tue, 11 Feb 2003 23:52:30 +0800
Message-ID: <00a401c2d1e5$95f0d6e0$030f77ca@proxy.seu.edu.cn>
To: <www-rdf-comments@w3.org>
Cc: "RDF-Interest" <www-rdf-interest@w3.org>, "Dan Brickley" <danbri@w3.org>

Some comments on RDF Schema as RDF/XML (Appendix A in RDF Schema Specification)

1. The definition of rdf:XMLLiteral 

<rdfs:Datatype rdf:about="http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral">
  <rdfs:isDefinedBy rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#"/>
  <rdfs:comment>The class of XML literal values.</rdfs:comment>

   <!--Add an element to specify that rdf:XMLLiteral is a subclass of rdfs:Literal(section 2.5).-->
   <rdfs:subClassOf rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>  


Although every instance of rdfs:Datatype is a subclass of rdfs:Literal (section 2.4, also rule rdfD 0c in section 4.3 of RDF Semantics Spec), we should also state that rdf:XMLLiteral is a subclass of rdfs:Literal because there is no simple way to represent the rule rdfD 0c in RDF/XML. 

2. The definition of rdfs:isDefinedBy 

<rdf:Property rdf:about="http://www.w3.org/2000/01/rdf-schema#isDefinedBy">
  <rdfs:isDefinedBy rdf:resource="http://www.w3.org/2000/01/rdf-schema#"/>

   <!--The following element is redundant, should be deleted. -->
  <rdf:type rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>

  <rdfs:subPropertyOf rdf:resource="http://www.w3.org/2000/01/rdf-schema#seeAlso"/>
  <rdfs:comment>The defininition of the subject resource.</rdfs:comment>
  <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
  <rdfs:domain rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>

3. The definitions of classes

Almost every class definition includes a rdfs:subClassOf element (some of them are trivial, such as specifying some class is an rdfs:subClassOf rdfs:Resource), except for the following:
rdf:XMLLiteral (See Point 1).

1) Specify rdfs:Literal and rdfs:List (even rdfs:Resource) be an rdfs:subClassOf rdfs:Resource. OR
2) Delete the element
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
within the definitions of classes: rdfs:Class, rdf:Property, rdf:Statement, rdfs:Container.

As we know every class (including rdfs:Class and rdfs:Resource) is an rdfs:subClassOf rdfs:Resource, see section 2.1, or rule rdfs7a in section 4.2 of RDF Semantics Spec.

4. Uniformly ordering sub-elements to gain better readability

For the definitions of properties, sub-elements ordering could be as follows:

For the definitions of classes, sub-elements ordering could be as follows:

End of my comments on RDF Schema as RDF/XML.

Thanks for your concern!

Yuzhong Qu
Dept. of Computer Science and Engineering
Southeast University, Nanjing 210096, P. R. China

Received on Tuesday, 11 February 2003 11:03:15 UTC

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