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Re: Subjects as Literals

From: Henry Story <henry.story@gmail.com>
Date: Tue, 6 Jul 2010 20:45:01 +0200
Cc: "Toby Inkster" <tai@g5n.co.uk>, "Linked Data community" <public-lod@w3.org>, "Semantic Web" <semantic-web@w3.org>, "Pat Hayes" <phayes@ihmc.us>
Message-Id: <9F112E0A-F509-42FD-8BD6-29F3D888F10B@bblfish.net>
To: Michael Schneider <schneid@fzi.de>

On 6 Jul 2010, at 14:03, Michael Schneider wrote:

> Toby Inkster:
> 
>> On Mon, 5 Jul 2010 17:43:17 -0500
>> Pat Hayes <phayes@ihmc.us> wrote:
>> 
>>> Well, nobody is suggesting allowing literals as predicates (although
>>> in fact the RDF semantics would easily extend to this usage, if
>>> required, and the analogous structures are allowed, and do have
>>> genuine use cases, in ISO Common Logic.)
>> 
>> Actually, I have suggested allowing them just to make things simpler -
>> URIs, blank nodes and literals would all be allowed in any position.
>> However, a statement with a literal in the predicate position would be
>> officially defined to have no meaning.
> 
> So, if 
> 
>    :s "lit" :o .
> 
> must not have a semantic meaning, what about
> 
>    "lit" rdf:type rdf:Property .

This would be possible to say. The problem is that there would be no
way on earth that anyone could come to an agreement as to what kind
of property "lit" was. Everyone could make up defend their choice. And
where there is no right or wrong, there is no meaning. Hence the above 
is undecidable.

What is the difference between the above and

   foaf:knows a rdf:Property .

Well we can dereference foaf:knows to find out what it means. This is
the canonical way to find it's meaning, and is the initial procedure we
should use to arbitrate between competing understandings of its meaning.

	Henry
Received on Tuesday, 6 July 2010 18:45:32 UTC

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