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Re: ruleml and RDF

From: Sandro Hawke <sandro@w3.org>
Date: Fri, 28 May 2004 09:59:52 -0400
Message-Id: <200405281359.i4SDxqnB009733@roke.hawke.org>
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: "Wagner, G.R." <G.R.Wagner@tm.tue.nl>, www-rdf-rules@w3.org, "Drew McDermott" <drew.mcdermott@yale.edu>


Bijan Parsia writes:
> If we're talking standards, much will depend on whether the W3C as a 
> body gives up the same syntax requirment on semantic web languages.

I think such a "requirement" was given up a long time ago, if it ever
existing.  The requirement is for scalable interoperation, and in
general (but perhaps not for rules) sticking to pure RDF seems like a
good way to do that.

Of course "the W3C as a body" doesn't speak very much, being a rather
enormous body.  In the team comment on SWRL [1] (which is the voice of
the W3C staff, NOT the voice of W3C [ie the W3C member or
"Director"]), I wrote:

      SWRL connects with RDF in two ways. The crucial connections is
      that RDF graphs can be directly expressed in SWRL (using only
      the obvious syntactic transformation) and they have exactly the
      same meaning. This allows SWRL rules to operate on and produce
      RDF data. It also allows a SWRL syntax to be used as an RDF
      syntax. 

And earlier I had written that SWRL should have an easy-to-read
syntax.  This matches the draft charter of a SWRL WG floated in
November, which suggested the rule language be an SYNTACTIC extension
of an RDF syntax.

Meanwhile, in the team comment I went on to say:

      A second connection is presented in section 6 of the submission,
      an RDF syntax for SWRL. The goal here is to allow RDF systems
      which know nothing of SWRL to store and process it as if it were
      any other RDF data. Ideally, when authoring RDF content, someone
      could add a quick rule in SWRL, just as they can add little bits
      of OWL. 

      This second connection is technically challenging to specify
      fully and correctly. The submission warns that for the encoding
      in section 6 to be used, non-standard RDF semantics must be
      used. We suggest that requiring non-standard semantics for a
      language is likely to cause a great deal of confusion and some
      market fragmentation. We greatly hope the path forward for SWRL
      includes an RDF encoding with full and correct RDF semantics,
      and an eye towards real user applications. 

... and I don't know of any way to do achieve this goal without
reifying the syntax of the rule language.  But maybe there is a way.
And this probably doesn't need to be critical path.

      -- sandro


[1] http://www.w3.org/Submission/2004/03/Comment
Received on Friday, 28 May 2004 09:59:44 GMT

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