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

Patrick,

> If I understand you, a specific RDF Schema (or collection of
> collaborative schemas) is the "program" which defines the strong data 
> typing -- but (presumably) if and only if for every property that
> can take a literal value there is defined one and only one range
> and that range defines the type of the property and all values
> the property can take. Once you allow multiple ranges, or fail
> to define a range for a property, you lose your strong data typing,
> right?

OK, so I thought we already decided in RDF Core WG to fix the range
constraints, so that they are conjunctive. Not having a range constraint
then "restricts" the type to the most general type ("Resource"). We
could also have a debate about how range constraints are to be used
("are they descriptive or prescriptive" I suppose is the right
question).

> To that end, RDF in essence allows strongly typed, weakly typed, and
> untyped property/value pairs all in the same knowledge base, depending
> on the mechanisms used for the particular property/value pairs in
> question.

Well, we really wanted to design RDF in such a manner that you could do
some processing without having to look at the schema (I believe the
original thinking was that firewall proxies, for example, would not want
to go and fetch a schema just to be able to look at some stuff going
through the firewall). In my mind that sort of rules out *mandating*
strong typing.

	- Ora

--
Ora Lassila  mailto:ora.lassila@nokia.com  http://www.lassila.org/
Research Fellow, Nokia Research Center
Chief Scientist, Nokia Venture Partners

Received on Monday, 8 October 2001 11:43:37 UTC