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Re: weird example in RDF-MT document...

From: Denny Vrandecic <dvr@aifb.uni-karlsruhe.de>
Date: Thu, 25 Jan 2007 21:58:13 +0100
Message-ID: <45B919E5.5020801@aifb.uni-karlsruhe.de>
To: www-rdf-logic@w3.org

Hi Axel,

this makes sense to me. Consider the following addition of the graph:

_:xxx dc:creator ex:Axel.
_:xxx dc:date "Jan-24-2007".
_:yyy dc:creator ex:Denny.
_:yyy dc:date "Jan-25-2007".

basically saying that the statement was done by you yesterday, and by me 
today, you would not want to entail that it was said by you today as well.

One could discuss if the identity of a statement is constituted by its 
three components, subject, predicate, object, but the standard clearly 
says it does not, and so the identity of a statement seems constituted 
by some other kind of magic (well, I'd go for an URI).

This also has the advantage that a statement with an URI as its 
identifier can actually be dynamic, like ex:Denny ex:listens_to 
ex:Jewel, which changes from time to time -- but nevertheless it could 
always have the same URI.


Axel Polleres wrote:
> Hi all,
> I was studying the RDF semantics document once again in some detail and 
> it looked to me I found a bug in an example in the end of section 3.3.1.
> Since I doubt that, I was asking myself whether somebody here can help 
> me to get the knot out of my head....
>    http://www.w3.org/TR/rdf-mt/#Reif
> In the end of that section, it is stated that
> "For example,
> _:xxx rdf:type rdf:Statement .
> _:xxx rdf:subject <ex:subject> .
> _:xxx rdf:predicate <ex:predicate> .
> _:xxx rdf:object <ex:object> .
> _:yyy rdf:type rdf:Statement .
> _:yyy rdf:subject <ex:subject> .
> _:yyy rdf:predicate <ex:predicate> .
> _:yyy rdf:object <ex:object> .
> _:xxx <ex:property> <ex:foo> .
> does not entail
> _:yyy <ex:property> <ex:foo> ."
>  This is at the very least strange for me...  and I think simply wrong.
> I mean, I understand what is *meant* to be said here, but of course
> the single triple graph
> _:yyy <ex:property> <ex:foo> .
> IS entailed by the former.
> Can anybody shed light on me? I must admit that I have some difficulties 
> to understand the non-normative reificaiton proposed in that section, 
> but I would assume that simple entailments still hold.
> I would be grateful if anybody can shed light on me or tell me whether 
> this was already answered elsewhere?
> Thanks,
> axel
Received on Thursday, 25 January 2007 20:59:41 UTC

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