[Top] [All Lists]

Re: [ontolog-forum] [Fwd: Re: {Disarmed} Re: OWL and lack of identifiers

To: Waclaw Kusnierczyk <Waclaw.Marcin.Kusnierczyk@xxxxxxxxxxx>
Cc: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Mon, 16 Apr 2007 09:54:45 -0500
Message-id: <p06230913c2493d96b7a2@[]>
>Pat Hayes wrote:
>>>  Re: Peter F Brown's post (Sat, 14 Apr 2007 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)

IHMC            (850)434 8903 or (650)494 3973   home
40 South Alcaniz St.    (850)202 4416   office
Pensacola                       (850)202 4440   fax
FL 32502                        (850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes    (06)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (07)

<Prev in Thread] Current Thread [Next in Thread>