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Re: Comment on the concepts document

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Tue, 22 Oct 2002 17:53:45 +0100
Message-Id: <5.1.0.14.2.20021022174405.00a52030@127.0.0.1>
To: Frank Manola <fmanola@mitre.org>
Cc: RDF core WG <w3c-rdfcore-wg@w3.org>

Frank,

OK, I think I've now got something closer to what you're suggesting.  My 
proposed section 2.3.2 now looks like this (specifically, the first 3 
paragraphs).

[[
2.3.2 Social meaning

RDF/XML documents, i.e. encodings of RDF graphs, can be used to make
representations of claims or assertions about the 'real' world.  But
not every RDF/XML document does so.

While the formal semantics of an RDF statement (triple) is that of a
distinct assertion, individual RDF statements may convey meaning that
is partly determined by the circumstances in which they are used.  For
example, in English, a statement "I don't believe that George is a
clown" contains the words "George is a clown", which, considered in
isolation, have the form of an assertion that George exhibits certain
comic qualities.  However, considering the whole sentence, no such
assertion is considered to be made.

Similarly, a collection of RDF statements having an assertional form
could be presented in a context that they are not understood to be
stating a truth.  Thus, there is a distinction between RDF expressions
that are asserted, and those that are not.

When an RDF graph is asserted in the web, its publisher is saying
something about their view of the world. Such an assertion should be
understood to carry the same social import and responsibilities as an
assertion in any other format. A combination of social (e.g. legal) and
technical machinery (protocols, file formats, publication frameworks)
provide the contexts that fix the intended meanings of the vocabulary
of some piece of RDF, and which distinguish assertions from other uses
(e.g. citations, denals or illustrations).

The technical machinery includes protocols for transferring information
(e.g. HTTP, SMTP) and file formats for encapsulating and labelling
information (e.g. MIME, XML). A media type, application/rdf+xml [RDF-
MIME-TYPE] is being registered for indicating the use of RDF/XML as
distinct from some other XML that happens to look like RDF. Issuing an
HTTP GET request and obtaining data with a "200 OK" response code is a
technical indication that the received data was published at the
request URI; but data received with a "404 Not found" response cannot
be considered to be similarly published information.

The social machinery includes the form of publication: publishing some
unqualified statements on one's World Wide Web home page would
generally be taken as an assertion of those statements. But publishing
the same statements with a qualification, such as "here are some common
myths", or as part of a rebuttal, would likely not be construed as an
assertion of the truth of those statements. Similar considerations
apply to the publication of assertions expressed in RDF.

Noting that there is no single human opinion about the truth of some
statements, the graph may further contain commentary for human
interpreters to indicate the realm of human interpretation that should
be applied. This means a graph may contain "defining information" that
is opaque to logical reasoners. This information may be used by human
interpreters of RDF information, or programmers writing software to
perform specialized forms of deduction in the Semantic Web.

When a user invokes an application that uses RDF, there is also a
social and technical context of invocation that determines some set of
RDF assertions that will be assumed to be true: the application itself,
and any RDF files that are passed to it. Garbage-in, garbage-out
applies: if the initial assumed facts are wrong or meaningless, the
results will have little value. No specific mechanisms for deciding or
evaluating the validity of any such assertions are defined here.
]]





At 08:26 PM 10/14/02 -0400, Frank Manola wrote:
>Graham--
>
>OK, we have progress on a couple of fronts:
>
>1.  I think my concerns about the mime type business are now put to rest 
>(at least as far as this section of the concepts document is concerned!).
>
>2.  I think we're communicating on the nature of the problem with sections 
>2.3.1 and 2.3.2.
>
>However, I don't think your suggested wording change below deals with it 
>adequately.  I agree with you on not letting "the prose get bogged down 
>here".  That's why my suggested changes were all in 2.3.2.  What you've 
>suggested is to change "assertion" to "claim" in 2.3.1 (but still 
>describing RDF as a "simple assertional language").  However, following 
>that, the first sentence in 2.3.2 seems to suggest that "claim" and 
>"assertion" are pretty much synonymous, and we're still faced with an 
>apparent contradiction when we encounter the end of the second paragraph 
>of 2.3.2, in which we "distinguish assertions from other uses [of RDF]."
>
>I think the mischief is done by not *immediately*, at the beginning of 
>section 2.3.2, pointing out that there is a difference between 
>understanding an RDF statement as an "assertion" in a formal sense as 
>described in section 2.3.1 (which after all, is about formal semantics) 
>and understanding an RDF statement as an "assertion" in its social meaning 
>(the subject of section 2.3.2).  This is why I tried to clarify this 
>distinction right away in my suggested change;  the word "assertion" is 
>being used in two somewhat different senses.  I agree that it's important 
>to make the point that RDF can be used to make honest-to-goodness 
>"assertions" (of fact) in the generally-understood sense of 
>"assertion".  However, it ought to be equally clear (and before we use the 
>word "assertion" too many times in section 2.3.2) that some "assertions" 
>[sense 1, from section 2.3.1] are not "assertions" [sense 2].  If this 
>distinction is made right away, I think the rest of the points being made 
>in this section become much clearer.
>
>--Frank
>
>Graham Klyne wrote:
>
>>At 11:28 AM 10/14/02 -0400, Frank Manola wrote:
>>
>>>Please refer to
>>>
>>>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Aug/0226.html
>>>
>>>as the issue raised there still exists in the subject document.
>>
>>OK, I think I see the problem.  In addressing the peripheral issues, I 
>>overlooked the headline comment...
>>Section 2.3.1 has:
>>[[
>>The RDF model theory treats RDF as a simple assertional language, in 
>>which each triple makes a distinct assertion, and the meaning of any 
>>triple is not changed by adding other triples. Based on the semantics 
>>defined in the model theory, it is simple to translate an RDF graph into 
>>a logical expression with essentially the same meaning.
>>]]
>>
>>And section 2.3.2 has:
>>[[
>>RDF/XML documents, i.e. encodings of RDF graphs, can be used to make 
>>representations of claims or assertions about the 'real' world.
>>When an RDF graph is asserted in the web, its publisher is saying 
>>something about their view of the world. Such an assertion should be 
>>understood to carry the same social import and responsibilities as an 
>>assertion in any other format. A combination of social (e.g. legal) and 
>>technical machinery (protocols, file formats, publication frameworks) 
>>provide the contexts that fix the intended meanings of the vocabulary of 
>>some piece of RDF, and which distinguish assertions from other uses (e.g. 
>>citations, denals or illustrations).
>>]]
>>
>>The problem seems to be that 2.3.1 seems to suggest that the triples 
>>cannot be expressed without being asserted.  I really don't want to let 
>>the prose get bogged down here.  Does this work for you:
>>[[
>>The RDF model theory treats RDF as a simple assertional language, in 
>>which each triple makes a distinct claim, and the meaning of any triple 
>>is not changed by adding other triples. Based on the semantics defined in 
>>the model theory, it is simple to translate an RDF graph into a logical 
>>expression with essentially the same meaning.
>>]]
>>#g
>>
>>-------------------
>>Graham Klyne
>><GK@NineByNine.org>
>
>
>--
>Frank Manola                   The MITRE Corporation
>202 Burlington Road, MS A345   Bedford, MA 01730-1420
>mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875

-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Tuesday, 22 October 2002 12:28:11 EDT

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