- From: Jan Grant <Jan.Grant@bristol.ac.uk>
- Date: Fri, 26 Apr 2002 11:23:47 +0100 (BST)
- To: RDFCore Working Group <w3c-rdfcore-wg@w3.org>
Dan asked me to send this on-list. Mostly niggles. The RDF Schema class and property system is similar to the type systems of object-oriented programming languages such as Java. I think this is disingenuous. It's not very like it at all, _particularly_ not like Java. Practices in schema and ontology creation (eg, making new superclasses when old subclasses are already inexistence; general frivolous attitude towards cycles) aren't common in most OO languages. rdfs:Resource The class Resource. Say more? rdfs:Class The concept of Class rdf:Property The concept of a property. rdfs:Literal This represents the set of atomic values, eg. textual strings. rdf:Statement The class of RDF statements. rdfs:Container This represents the set Containers. rdf:Bag An unordered collection. rdf:Seq An ordered collection. rdf:Alt A collection of alternatives. rdfs:ContainerMembershipProperty The container membership properties, rdf_1, ... rdf_n, all of which are sub-properties of 'member'. We've got concepts, classes and sets here. I know it's really tedious to repeat the same phrase over and over, but people might ask: "do RDF statements form a class? why not a set? What's this set Containers? etc." rdfs:Class The class of all _rdfs:Class_es rdf:property etc. Literal: don't say "atomic". Atomic means "indivisible"; literals (even the simple ones we're working with) have structure. That structure might not be expanded in terms of nodes and arcs, but it's wrong to say "the structure doesn't appear in the graph". It _does_ appear, but it's bundled up into a literal node. Call it "The Class of literal values" and point to the MT for a definition. The only other thing is that I'd avoid rdf:_n unless you can italicise or otherwise show that "rdf:_n" isn't one of these. I'd also (I know it's late in the game) be inclined to float the suggestion of "fixing" the rdfs:subClassOf & co. properties, deprecating these in favour of names that are the right way around according to M+S, and including entailment rules to show that they're the same thing. (just make them circularly subproperties of their renamed versions) - particularly if we're switching namespace. -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk Whose kung-fu is the best?
Received on Friday, 26 April 2002 06:24:08 UTC