Re: Data Model question - using a subject as a predicate

At 12:10 PM 10/5/00 +0100, David Allsopp wrote:

>Hello all,
>
>Another question about the RDF Data Model:
>
>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>In the formal model we have:
>
>1. There is a set called 'Resources'
>2. There is a set called 'Literals'
>3. There is a subset of 'Resources' called 'Properties'
>4. There is a set called 'Statements', each element of which is a triple
>of the form {pred, sub obj}
>
>where pred is a property (member of 'Properties'), sub is a resource
>(member of 'Resources') and obj is either a resource or a literal
>(member of 'Literals').
>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
>This seems to imply that a resource already being used as a subject or
>object (i.e. not currently a member of the subset 'Properties') can
>later be used as a predicate (by the addition of a further triple to the
>model). This resource then becomes a member of the subset 'Properties').
>
>Is this correct?  Can someone give a practical example where this might
>be useful, or at least make sense?

Yup.

Take it the other way round:  suppose you want to make an assertion about a 
property, then it must appear as a subject of some statement.

Consider rdfs:subPropertyOf (see RDF schema specification).

#g

------------
Graham Klyne
(GK@ACM.ORG)