W3C home > Mailing lists > Public > www-rdf-logic@w3.org > January 2001

Properties, predicates and resources

From: Miles Sabin <MSabin@interx.com>
Date: Mon, 22 Jan 2001 13:44:38 -0000
Message-ID: <23CF4BF2C499D411907E00508BDC95E116FB83@ntmews_01.interx.com>
To: www-rdf-logic@w3.org
According to rdfms 5: Formal Model for RDF,

  3. There is a subset of Resources called Properties

In rdfms 2.1: Basic RDF Model,

  Resources are always named by URIs plus optional anchor IDs.

In 3.1: Container Model,

  The membership relationship between [a] container resource
  and the resources that belong in the collection is defined by
  a set of properties defined expressly for this purpose. These
  membership properties are named simply "_1", "_2", "_3", etc.

Jointly these seem to imply that each of "_1", "_2", "_3" are
resources and hence have a URI(-ref). Given that they're part of 
core RDF I'd expect them to have cannonical absolute URI(-ref)s.

What would they be? Something like,

  http://www.w3.org/1999/02/22-rdf-syntax#_1"
  http://www.w3.org/1999/02/22-rdf-syntax#_2"

etc.?

Also, in 4.1 Modelling Statements,

  To model statements RDF defines the following properties:

  ...

  predicate
    The predicate property identifies the original property in
    the modeled statement. The value of the predicate property
    is a resource representing the specific property in the
    original statement.

I'm not entirely clear on whether or not the resource which _is_
a property (from clause 3 in the formal model) is intended to be 
identical to the resource which _represents_ a property in a
reification (from the clause in 4.1 quoted above). Pretty clearly
things can represent themselves, but I'm not sure that that's the 
intent of the definition here. In particular, it contrasts with 
the neighbouring definitions of the 'subject' and 'object' 
properties, both of which appear to reuse the URIs from the 
reifyee and don't make any mention of any sort of representing
resource.

What's the correct interpretation? Do properties appear directly
in reifications? Or indirectly via a distinct representative
resource?

Cheers,


Miles

-- 
Miles Sabin                               InterX
Internet Systems Architect                5/6 Glenthorne Mews
+44 (0)20 8817 4030                       London, W6 0LJ, England
msabin@interx.com                         http://www.interx.com/
Received on Monday, 22 January 2001 08:45:20 GMT

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