W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2001

Re: Activating lower layer issues

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 28 Jun 2001 11:06:20 -0500
Message-Id: <v04210108b76104508bda@[205.160.76.181]>
To: Graham Klyne <Graham.Klyne@Baltimore.com>
Cc: w3c-rdfcore-wg@w3.org
>At 07:04 PM 6/26/01 +0100, Brian McBride wrote:
>>Graham, you have made a proposal for an absract syntax and semantics.  I am
>>assuming that you feel pretty neutral about the actual concrete form of
>>the syntax and that n-triple can represent everything you need at the
>>syntactic level.  If that is so, then we can focus on the question of
>>reification on the semantics rather than the syntax.
>
>Yes, with one proviso:
>
>Some semantics depend on an interpretation of more than one triple 
>used in concert.  Following the style of attaching interpretations 
>to syntax productions, it may be necessary use a "model syntax" that 
>is more complex than the minimal syntax needed to describe N-triple.

Graham, I have a strong worry about doing this in the revised 
standard.  "used in concert" is just a way to say that there is a 
syntactic construction which is not in fact explicitly encoded in RDF 
content.  It would mean that the criteria for wellformedness were not 
explicitly represented in the syntax, unless we introduced some new 
syntax (not just some new syntactic classes) to actually encode the 
ranges of these 'larger' structures. In effect, it allows for 
arbitrarily complex syntactic specifications to be smuggled into the 
RDF model invisibly. To call the n-triple encoding 'parsable' is 
misleading, if some of those 'parsings' are not in fact in conformity 
to the syntactic classes to which the semantics is attached.

Look, here is a universal parsable syntax for all of the world's languages:
<expression> ::= <unicode-char>*
but we wouldnt normally say that this is parsable in any useful sense.

Pat


>Otherwise, I fully agree that everything can be based on a concrete, 
>parseable representation that we call N-triple (an important 
>property of which is that, modulo trivial matters like statement 
>ordering, there is only one way to represent any given RDF graph).
>
>#g
>
>
>------------------------------------------------------------
>Graham Klyne                    Baltimore Technologies
>Strategic Research              Content Security Group
><Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
>                                <http://www.baltimore.com>
>------------------------------------------------------------

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Received on Thursday, 28 June 2001 12:06:31 EDT

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