Pat Hayes wrote:
On Jul 2, 2010, at 12:07 AM, Nathan wrote:
Pat Hayes wrote:
On Jul 1, 2010, at 11:49 PM, Nathan wrote:
Pat Hayes wrote:
On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote:
"A literal may be the object of an RDF statement, but not the subject
or the predicate."
Just to clarify, this is a purely syntactic restriction. Allowing
literals in subject position would require **no change at all** to
the RDF semantics. (The non-normative inference rules for RDF and
RDFS and D-entailment given in the semantics document would need
revision, but they would then be simplified.)
I have to wonder then, what can one all place in the s,p,o slots
without changing the RDF semantics? literal and bnode predicates for
instance? variables or formulae as in n3?
read as: if a new serialization/syntax was defined for RDF what are
the limitations for the values of node/object and relationship
specified by the RDF Semantics?
None at all. The semantics as stated works fine with triples which
have any kind of syntactic node in any position in any combination.
The same basic semantic construction is used in ISO Common Logic,
which allows complete syntactic freedom, so that the the same name
can denote an individual, a property, a function and a proposition
all at the same time.
Pat
PS. Its not a dumb question :-)
thus is N3 valid RDF? (I read yes, but want/need to hear that's right!)
Well, no. It depends what you mean by 'valid RDF'. N3 obviously has a
lot of syntax that goes way beyond what is legal in RDF, so its not
valid RDF. But if you mean, the basic RDF semantics can be extended to
cover all the constructs in N3 (without completely breaking) then yes,
it can. In fact, N3 is a subset of Common Logic, and the same basic
semantic construction of RDF works for all of CL. But it would be a
real extension, in that all the 'extra' syntax of N3 (notably, the graph
literals idea) would need to have its semantics specified explicitly. It
wouldn't come for free.
Hope I've answered your question (?)
perfectly, thanks!