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Re: the meaning of RDF tokens

From: Frank Manola <fmanola@mitre.org>
Date: Thu, 13 Feb 2003 14:08:22 -0500
Message-ID: <3E4BED26.9EBA2D54@mitre.org>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: www-rdf-comments@w3.org

Peter--

Thanks for this comment.  I believe this is roughly the same point you
made in your review of the pre-last-call documents of 26 December 2002,
where you said

> The Primer starts the unfortunate blurring between RDF, a simple formalism,
> and the entirely of human understanding in its talk about knowing the
> ``exactly what is meant by'' http://purl.org/dc/elements/1.1/creator.  It
> would be much better to avoid anything in the Primer that even hints that
> an  RDF processor will be able (or, worse, required) to understand exactly
> what is meant by such things, as their meaning includes a gigantic portion
> that is outside of RDF.

Can you confirm that?  In my response to your original comment, I had
said:

> When I referred to a program "that understands 
> http://purl.org/dc/elements/1.1/creator" I was thinking in terms of a 
> program *written* to understand that particular term (or written to 
> behave according to that term's definition when it encountered it) 
> rather than a generic RDF processor that somehow sucked in that 
> "understanding".  But I see how the problem you mention can arise.  I'll 
> try to make that clearer (I think it's still necessary to mention 
> "programs", but I agree that the limitations of what "understanding" RDF 
> provides to those programs needs to be clarified).

Do you believe that this sort of clarification will address the issue
you raise? I generally understand your concern as being to clearly
separate the meaning that RDF itself specifies from any additional
meaning that has to be read into such tokens by humans (and programs
they write based on that additional meaning).  Is that correct?  I'll
run the actual proposed rewrite by you if you like (as soon as I come up
with it).

In accordance with the change recording process we're using, I had
assigned your original comment a change id of #primerLCC-010.  If you
feel that this new comment is distinct from that one, could you please
clarify the difference (and I'll add an additional change)?  Thanks
again.

--Frank


"Peter F. Patel-Schneider" wrote:
> 
> The RDF primer, in Section 2.2, states
> 
>         Using URIrefs as subjects, predicates, and objects in RDF
>         statements allows us to begin to develop and use a shared
>         vocabulary on the Web, reflecting (and creating) a shared
>         understanding of the concepts we talk about. For example, in
>         the triple
>                 ex:index.html  dc:creator  exstaff:85740 .
>         the predicate dc:creator, when fully expanded as a URIref, is an
>         unambiguous reference to the "creator" attribute in the Dublin Core
>         metadata attribute set (discussed further in Section 6.1, a
>         widely-used set of attributes (properties) for describing
>         information of all kinds. The writer of this triple is effectively
>         saying that the relationship between the Web page (identified by
>         http://www.example.org/index.html) and the creator of the page (a
>         distinct person, identified by
>         http://www.example.org/staffid/85740) is exactly the concept
>         identified by http://purl.org/dc/elements/1.1/creator. Moreover,
>         anyone else, or any program, that understands
>         http://purl.org/dc/elements/1.1/creator will know exactly what is
>         meant by this relationship.
> 
> This appears to me to state that the meaning of tokens in RDF *is*
> their commonly agreed on meaning, regardless of how that meaning is
> specified.  If so, this means that RDF reasoners are responsible for
> implementing this meaning.
> 
> Is this actually the case?  If so, how can RDF reasoners be implemented?
> If not, please explain what the above quote means.

-- 
Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-8752
Received on Thursday, 13 February 2003 14:08:31 GMT

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