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Re: Annotations use case

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Sun, 9 Feb 2003 00:04:25 +0000
Message-ID: <15941.39689.554569.514467@merlin.horrocks.net>
To: Jim Hendler <hendler@cs.umd.edu>
Cc: Mike Dean <mdean@bbn.com>, webont <www-webont-wg@w3.org>

On February 7, Jim Hendler writes:
> 
> At 7:42 -0800 2/7/03, Mike Dean wrote:
> >  > and recommends use of XML comments instead - ugly, but I could live with)
> >
> >This is problematic in that XML comments aren't preserved in
> >the RDF graph.  It precludes round-tripping of content.
> >
> >	Mike
> 
> no, no, no - that's my whole point!  - things one wants in the graph 
> go in RDFS:comment -- i.e. you need them to round trip.  Things one 
> adds as "comments" in the traditional programming language sense 
> should be lost (i.e. when you roundtrip C code the comments are lost) 
> and thus should be in XML comments instead!

The C code metaphor is not valid - the "exchange syntax" for C
programs is the source text, including comments, and not the compiled
code. It would not be acceptable if comments were stripped out by
tools (such as editors) that work with C source code.

Using XML comments raises all sorts of issues and seems to be in
conflict with declaring RDF to be the exchange syntax. It isn't easy
to see how XML comments would be handled by an editor, and how they
would be associated with different elements of an ontology. It is
certainly very unlikely that all tools would do this in a uniform way,
so we would loose any real tool interoperability - how acceptable
would it be if any time I use a different ontology editor I
loose/trash all the comments in my ontology (consider the C
programming analogy)?

Just look at some of the things that are typically done with comments
(e.g., in the DAML+OIL ontology library, where they are often used to
attach natural language rubrics to classes) and ask yourself (a) if
this could be done using XML comments (while maintaining tool
interoperability), and (b) if it is appropriate that such comments
affect entailment in the ontology language.

Ian

> 
> -- 
> Professor James Hendler				  hendler@cs.umd.edu
> Director, Semantic Web and Agent Technologies	  301-405-2696
> Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
> Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler
> 
Received on Saturday, 8 February 2003 19:05:21 GMT

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