W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > February 2002

Re: reification test case

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Wed, 6 Feb 2002 12:15:51 -0600
Message-Id: <p0510143ab88720358a17@[65.212.118.208]>
To: "Jos De_Roo" <jos.deroo.jd@belgium.agfa.com>
Cc: w3c-rdfcore-wg@w3.org
>[...]
>
>>  There's something wrong with Euler, then.  It isn't valid to go from
>>
>>  <some huge graph with _:s1 in it>
>>  <an exactly similar graph with _:s2 substituted for _:s1>
>>  _:s1 foo baz
>>
>>  to
>>  _:s2 foo baz.
>>
>>  no matter what is in the huge graph.

See my reply to Graham, I think I was misunderstanding y'all. Sorry 
about that. I thought you were inferring triples and adding them to a 
graph, but you were talking about entailment between distinct graphs 
(so the use of the same nodeID is irrelevant, right?)

>
>well Pat, we get that
>
>   <http://example.org/eg#s> <http://example.org/eg#p> _:s1 .
>   <http://example.org/eg#s> <http://example.org/eg#p> _:s2 .
>   _:s1 <http://example.org/eg#q> <http://example.org/eg#v> .
>
>is *not* entailing
>
>   _:s2 <http://example.org/eg#q> <http://example.org/eg#v> .

Well, now. Is that conclusion supposed to be a separate graph all on 
its own? If so, you should get this entailment (just from the third 
triple in the first graph.)
If its supposed to be conjoined to the first three triples, so that 
those two _:s2's really are the same node, then you should not get 
the entailment.

>
>even
>
>   <http://example.org/eg#s> <http://example.org/eg#p> _:s1 .
>   <http://example.org/eg#s> <http://example.org/eg#p> _:s2 .
>   _:s1 <http://example.org/eg#q> <http://example.org/eg#v> .
>
>is *not* entailing
>
>   _:s1 <http://example.org/eg#q> <http://example.org/eg#v> .
>

Hmm, that seems odd by anyone's standards. Why not? Its the very same 
triple, right? So even if you add it to the graph, you would get the 
same graph.

>and even
>
>   <http://example.org/eg#s> <http://example.org/eg#p> _:s1 .
>   _:s1 <http://example.org/eg#q> <http://example.org/eg#v> .
>
>is *not* entailing
>
>   _:s2 <http://example.org/eg#q> <http://example.org/eg#v> .

That should be entailed, again by anyone's standards. It is always OK 
to say an existential statement again using a different bound 
variable, even inside the same graph.

>
>but
>
>   _:s1 <http://example.org/eg#s> <http://example.org/eg#p> .
>   _:s1 <http://example.org/eg#q> <http://example.org/eg#v> .
>
>is entailing
>
>   _:s2 <http://example.org/eg#q> <http://example.org/eg#v> .

?? Why is this different from the previous case??

Pat
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Received on Wednesday, 6 February 2002 13:15:14 EST

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