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RE: test case: Test case A and reification

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Tue, 9 Jul 2002 10:53:06 +0100
To: "pat hayes" <phayes@ai.uwf.edu>, "Brian McBride" <bwm@hplb.hpl.hp.com>
Cc: <w3c-rdfcore-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDGEEOCEAA.jjc@hplb.hpl.hp.com>


Following on from my reply
http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jul/0047.html

I highlight:

> Er.... why not? In the current stake proposal, they all denote the
> string "10" (which conforms to the lexical form requirements of both
> xsdr:decimal and xsdr:string, so everything is fine.)

But Brian is in the context of the f2f suggestion that the denotation of
literals depends on the property and the literal, not just the literal.


Brian:
> >I confess I find this rather bizarre.  In the case where the object
> >of a statement is a literal, then the value of the rdf:object
> >property of the reification of that statement denotes a syntactic
> >entity, otherwise it denotes a semantic one.  (Sorry that doesn't
> >sense to a logician, but Pat'l know what I mean.)
Pat:
> Well, it is bizarre, but the bizarritude arises from the fact that we
> have made these pieces of syntax denote themselves, thereby neatly
> confusing the syntactic and semantic domains by putting the former
> into the latter.

Ahh, this links up better with the f2f.

Brian:
> >Is that what we mean to say?
> >
> >If the answer to test case A is yes, then we need an non-entailment test:
> >
> >   <s> <p> "a" .
> >   _:s rdf:subject <s> .
> >   _:s rdf:predicate <p> .
> >   _:s rdf:object "a" .
> >   _s: rdf:type rdf:Statement .
> >
> >where _:s is a reification of the first statement
> >
> >does not entail:
> >
> >   <s> <p> _:o .
> >   _:s rdf:object _:o .
Pat:
> Again, I think this is valid in the current 'stake' proposal (for
> literals and urirefs).

This entailment holds for literals, and the corresponding entailment holds for
urirefs.

>                     And if literals were semantically untidy, then
> any entailment from distinct literal nodes to common bnodes would be
> invalid. In other words, I don't think reification introduces any new
> issues.

So if the object is a uriref or bNode we enatil:

  <s> <p> _:o .
 _:s rdf:object _:o .

but if the object is a literal then we don't.

>           The issue is: If we allow untidy literal nodes, when can we
> assume that two literals denote the same thing? Answer: when they are
> the same *node*. It's the nodes that do the denoting, not the labels.
> Then it all works coherently, including reification and containers
> (that is, containers are weak; eg datatyping a container doesn't
> datatype its contents. But we knew that already, right?)
>


Jeremy
Received on Tuesday, 9 July 2002 05:53:18 EDT

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