Not wanting to keep beating this particular drum, but some things just
have to be responded to.
On Jul 5, 2010, at 1:36 PM, Sampo Syreeni wrote:
On 2010-06-30, Hugh Glaser wrote:
RDF permits anyone to say anything about anything . . . except a
literal if it is the subject of the property you want to use for
the description.
The way I see it, the main reason for this restriction is that the
data is supposed to be machine processable. Literals rarely are,
especially in their original, plain form.
This objection strikes me as completely wrong-headed. Of course
literals are machine processable.
I mean, suppose we allowed literals as subject, predicate and
object. What does it really mean if I say "Sally"@en "likes"@en
"Mike"@en?
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.) But it is easy to give
'ridiculous' examples for any syntactic possibility. I can write
apparent nonsense using nothing but URIs, but this is not an argument
for disallowing URIs in RDF.
I'd argue pretty much nothing processable. That's because literals
tack on an arbitrary, limited number of type specifiers (type and
perhaps language) to textual data, and neglect everything beyond
that. That is not how full disambiguation is done; it's how a human
processor *minimally* disambiguates a piece of text, without making
it unambiguous.
This is WRONG. The type specifiers *completely* disambiguate the text
in the body of the literal. Really, this is not a topic for debate in
a public email list. Just check the actual RDF specifications, in
particular http://www.w3.org/TR/rdf-mt/#dtype_interp . For plain
literals, the meaning of the literal is the string itself, a unique
string of characters. Again, this is stated in the RDF specification
documents as a normative part of the RDF spec.
With Schema derived or otherwise strictly derived types, the level
of disambiguation can be the same as or even better than with URI's,
true. But then that goes the other way around, too: URI's could take
the place of any such precise type.
No, they cannot. For numbers, for example, one would need infinitely
many URIs; but in any case, why bother creating all these URIs? We
have (universally understood) names for the numbers already, called
numerals. For dates, times and so forth, there are many formats in use
throughout human societies, of course. That is WHY the work of
establishing datatype standards work was done. To ignore all this, to
reject a widely accepted standard, and advocate reversion to a home-
made URI scheme seems to me to be blatantly irresponsible.
Pat Hayes
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