W3C home > Mailing lists > Public > www-rdf-interest@w3.org > September 2002

Re: Can a property not have a uriref?

From: Zhang Jeff <jeffzhang726@yahoo.com.cn>
Date: Wed, 18 Sep 2002 09:28:38 +0800 (CST)
Message-ID: <20020918012838.15765.qmail@web20701.mail.yahoo.com>
To: www-rdf-interest@w3.org

 --- Sandro Hawke <sandro@w3.org> 的正文:> 
> > I had assumed that all predicates must be named by
> some uriref - this 
> > seems obvious where a predicate appears in a
> simple s o p triple.
> ...
> > But today I thought of another possible counter
> example (where we are 
> > dealing with reification) that may actually make
> sense in some 
> > circumstances.
> Actually, there are lots of times when it makes
> sense to have arcs
> without URIRef labels, even without reification. 
> Two that come to
> mind are Currying and using properties when you only
> know their
> unambiguous properties.

If you really want it, why not use an instance of
"http://www.w3.org/...#Property" which is just
a property without any specific meaning?
OR introduce an "anonymous property",into RDF
OR in application level,such as
"http://www.mycompany.com/unknowProp"  typed as
rdf:Property ? It is easy to deal it as a "general
property" in application level.
(I don't have much knowledge of AI or theories of
models or math and I just can not see the complexity
of this problem. Is it really so difficult? )
And,is there any similar concepts in logics or
relation algebra or other knowledge representations?

> > Is this allowable/ make sense? If affirmative -
> then a property need not 
> > have a uriref?
> It makes perfect sense, but as far as I know it is
> not legal in RDF
> M&S or in the new RDF Core WG drafts.  This bothers
> some of us, but
> there are trade-offs.  I write my code to not rely
> on this artificial
> restriction, but maybe there are good reasons to
> rely on it.
> > BTW - "Property" and "predicate" appear to be used
> interchangeably - are 
> > they the same concept?
> As I understand it, a Property object acts as a
> predicate in an RDF
> statement.  I can kind of imagine using a Property
> as something else,
> or using something else as a predicate, but I think
> the distinction
> seems to cause more confusion than it's worth.
>       -- sandro

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Received on Tuesday, 17 September 2002 21:28:40 UTC

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