RE: Literals (Re: model theory for RDF/S)

> Also agreed, but I sense that there are quite a number of 
> people that are
> not in favour of RDF having a datatype system.  

RDF need not itself have a built-in data type system in order
for there to be simple but effective means to employ data type
systems within RDF based applications.

If all values in RDF graphs are URI labeled resources, then
standardized data type schemes can be defined in terms of a
URI scheme and RDF can remain neutral (and more flexible, and
more future proof, etc.)

> Also agreed.  Further, the only reason that DAML+OIL has its 
> own datatype
> mechanism is that there is not one in RDF(S).

I don't see anything wrong with how DAML encorporates XML Schema
data types. It may be, though, that such data type mechanisms
should live at a lower level, namely RDFS -- or maybe not. I'm
undecided about that.

They don't, though, belong IMO at the RDF level, in the graph.

One of the challenges right now about using RDF and SW technologies
is that we're all still feeling our way along the "frontier", and
the less that is defined in the standards and provided in standards
conformant tools, the more we have to roll our own -- and it's
not always nice to have to do that, dispite the freedom that one
may have in doing so.

To that end, I do agree that several key mechanisms need to be
"pushed down" a level or two in the general architecture, generalized,
standardized, and broadly supported. Typed data literals is one.
Semantic primitives for relation types (transitivity, super/subordination,
etc.) is another. Scoping/qualification of statements is yet another. 
Most of these seem (to me) to belong in the RDFS layer or in a layer 
deriving from a fusion of RDFS and DAML+OIL.

(but not at the RDF layer ;-)

Cheers,

Patrick

--
Patrick Stickler                      Phone:  +358 3 356 0209
Senior Research Scientist             Mobile: +358 50 483 9453
Nokia Research Center                 Fax:    +358 7180 35409
Visiokatu 1, 33720 Tampere, Finland   Email:  patrick.stickler@nokia.com

Received on Wednesday, 3 October 2001 03:45:10 UTC