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comment - RDFTM: Survey of Interoperability Proposals

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 08 Mar 2005 09:26:29 -0500 (EST)
Message-Id: <20050308.092629.33012614.pfps@research.bell-labs.com>
To: public-swbp-wg@w3.org

This is collection of comments on RDFTM: Survey of Interoperability
Proposals http://www.w3.org/2001/sw/BestPractices/RDFTM/survey-2005-02-24.


First, however, a disclaimer:  I am a long-time skeptic of the entire Topic
Maps paradigm.  I have tried several times to determine whether there is
something interesting in Topic Maps and each time I have been unsuccessful.
My skepticism colors many of these comments.


The first problem that I see with the document is that it doesn't define
the two paradigms.  There are no references to any of the defining RDF
documents.  There are several references that could be considered to be
defining Topic Maps - however, these do not show up until very late in the
text and thus cannot be considered to be a definition for the purposes of
this document.

This lack of a definition matters for reasons from both the RDF and the
Topic Maps side.  RDF has undergone a significant change in the last few
years from a pre-theoretic language with no firm foundation (see Resource
Description Framework (RDF) Model and Syntax Specification
http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/) to a full-fledged logic
(see RDF Semantics http://www.w3.org/TR/rdf-mt/).  Which version of RDF is
meant in the document?  Which version of RDF to the interoperability
proposals refer to?  As well, what is the place of RDFS in the document?
Is it included?  Is it excluded?  

Topic Maps also are undergoing change, from the ISO definition (ISO/IEC
13250:2000 Topic Maps: Information Technology -- Document Description and
Markup Languages, Michel Biezunski, Martin Bryan, Steven R. Newcomb, ed., 3
Dec 1999.  http://www.y12.doe.gov/sgml/sc34/document/0129.pdf) to some
recent draft proposals (Garshol, Lars Marius; Moore, Graham: ISO/IEC 13250:
Topic Maps - Data Model (Final Committee Draft, 2005)
http://www.isotopicmaps.org/sam/sam-model/ and Durusau, Patrick; Newcomb,
Steven R.: ISO/IEC 13250: Topic Maps - Reference Model (Working Draft,
2004) http://www.isotopicmaps.org/tmmm/TMMM-4.6/TMMM-4.6.html).  Which
version of Topic Maps is under consideration?  Does it matter?


The second problem is that many of the interoperability proposals predate
the finalization of the RDF Semantics.  Their current applicability is thus
very suspect.  The document needs to carefully consider this aspect of each
proposal. 


The third problem is that RDF and Topic Maps belong to different
categories, at least so far as I can determine.  RDF is now a
formally-specified logic with a model-theoretic semantics.  Topic Maps is
not.  This difference matters, and needs to be taken into account in every
discussion of the relationship between RDF and Topic Maps.  At best, there
needs to be some way to determine that the interoperability proposals
preserve logical equivalence on the RDF side.  At worst, there is no point
in doing any mappings, as RDF and Topic Maps are simply incomparable.  [For
indications why this might be the case, consider that Topic Map merging as
defined in http://www.isotopicmaps.org/sam/sam-model/ is claimed to not
remove all redundant information in a topic map.  How then can it be
determined whether a mapping is reasonable?  As well, the procedure defined
therein does not terminate.]


The fourth problem is that I do not see any utility for the document as a
W3C Working Note.  What does the note have to do with any real output of
the task force?  Perhaps the task force needs this document for its
internal deliberations, but in my opinion this doesn't require a
full-fledged note.  (Consider the situation in the WebOnt working group
where there were many internal documents used to produce OWL.  These
documents are recorded in the records of the working group kept by W3C, but
did not become W3C Working Notes.)


Peter F. Patel-Schneider
Bell Labs Research
Received on Tuesday, 8 March 2005 14:36:56 UTC

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