Re: DAML+OIL (March 2001) released

Peter Crowther <Peter.Crowther@melandra.com> writes:

> > From: Jonas Liljegren [mailto:jonas@rit.se]
> > I would like to see these examples formulated in RDF, since I can't
> > understand exactly whay you mean with 'is a kind of', 'are equal'...
> 
> Sorry, Jonas, I skimmed the vital three lines in your original email and
> missed the key point that fixes my four examples:
> 
> > The important thing here is to make { xsd:element rdfs:subClassOf
> > rdfs:Literal }.  That's the way to integrate XML schema into RDF.  No
> > need for alienating DAML or use those extra property types.
> 
> With this point noted, I retract my scatter-gun comments and extend an
> apology instead.  RDFS prohibits anything being a subclass of a literal, so
> my first two examples go away.  RDF also prohibits using a literal as a
> domain, so my third and fourth examples go away.  Neat!
> 
> Now all we need to do is to define { xsd:element rdfs:subClassOf
> rdfs:Literal } in some appropriate place.

Eh... Wait.

I read from RDFS spec:

        Although the RDF data model does not allow for explicit
        properties (such as an rdf:type property) to be ascribed to
        Literals (atomic values), we nevertheless consider these
        entities to be members of classes (e.g., the string "John
        Smith" is considered to be a member of the class
        rdfs:Literal.)

             Note: We expect future work in RDF and XML data-typing to
             provide clarifications in this area.


Don't mind the current state.  We will fix this.  (Unless you are
exploiting it as a kind of hack to make some old inference engine
work.)

The RDF spec tells us how to handle typed literals.  And the new
DAML+OIL follows that:

        http://www.w3.org/TR/REC-rdf-syntax/#ex-NonBinary


The thing I would like to add here is:

The resource with the value property represents the literal.  This
resouce can be used for holding metadata about the literal.  The most
important part of metadata is the type of literal.  The resource will
be typed as some subClassOf Literal.

Anywhere a literal is expected, you can instead have a resource
representing that literal, with a value property.

I wrote about it previously here:

        http://lists.w3.org/Archives/Public/www-rdf-interest/2000Mar/0085.html
        http://lists.w3.org/Archives/Public/www-rdf-interest/1999Nov/0107.html


-- 
/ Jonas Liljegren

The Wraf project http://www.uxn.nu/wraf/
Sponsored by http://www.rit.se/

Received on Thursday, 29 March 2001 11:31:04 UTC