On Jul 6, 2010, at 1:45 PM, Henry Story wrote:
On 6 Jul 2010, at 14:03, Michael Schneider wrote:
Toby Inkster:
On Mon, 5 Jul 2010 17:43:17 -0500
Pat Hayes <pha...@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.
True (though you use "undecideable" here not in its technical sense, I
presume) but the same is true for any RDF at all.
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.
Not according to the RDF specs, you can't. That is, you can (maybe)
dereference it, but what you get has no bearing upon its (official)
meaning. Maybe it should, but that idea needs a LOT of work to get
straight. It is one proposal in the RDF2 wish-list, in fact.
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.
Whoo, I doubt if that idea is going to fly. I sincerely hope not.
Using that, how would you determine the meaning of the DC vocabulary?
Pat
Henry
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