>Pat Hayes wrote:
>>> Re: Peter F Brown's post (2007年4月14日 09:35:14)
>>>
>>> Peter writes:
>>>
>>> "
>>> The spec is clear, yesS. but an object is not the same thing as the
>>> address of the object - (according to the RFC, I *am* my address): the
>>> object needs identity as much as the address of it does. That is where I
>>> feel this axiom of the W3C falls downS
>>> "
>>>
>>> Clearly there is a problem here. But we should be careful to
>>> distinguish confusedly designed frameworks from confused documentation
>>> of well-designed ones.
>>>
>>> While RDF specifications, for example, are relatively clear and sound,
>>> the RDF primer provides an abundance of examples such as:
>>>
>>> ex:index.html exterms:creation-date "August 16, 1999" .
>>> ex:index.html dc:language "en" .
>>>
>>> supposed to state that "August 16, 1999" is the creation date of a page
>>> and "en" is he language of a page, while both are literal strings and
>>> *not* identifiers for a date and a language, respectively.
>>
>> What?? Why should a string not be an identifier? In fact, it seems to
>> me that *all* identifiers are strings. And the second example uses a
>> language tag which is taken from an Internet standard for language
>> tagging: what could be a better example of an agreed identifier? Why is
>> this confused?
>
>Hold on. It is not whether something is a string or not which counts,
>but how it is to be interpreted. Of course, "August 16" can be an
>identifier for anything you may wish. But it is a string, not a date. (01)
Of course it is not a date, but it is (using widely accepted
conventions) an *identifier* of a date. (02)
>But as the object of a triple, "August 16" is a literal, not a URI, and
>in RDF, a literal is (supposed to be) self-referential. (03)
True. But it is an easy extension to the RDF interpretation to go on
to interpret that string as denoting a date. RDF was always intended
to be used as part of larger systems of conventions and
interpretations. (04)
And this is, after all, an example from a primer. The best way to
express this in RDF would be to use a typed literal with the xsd:date
system, which is required to exactly denote a date; but the primer
had not covered datatyping at this point. (05)
Pat
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