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Re: vass-01 flat layering

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 27 May 2003 16:19:22 -0500
Message-Id: <p05210607baf9857cfe53@[10.0.100.24]>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: w3c-rdfcore-wg@w3.org

>Danbri and I have been discussing issue:
>
>   http://www.w3.org/2001/sw/RDFCore/20030123-issues/#vass-01
>
>Its quite hard to get a crisp quote of the problem from the email 
>thread but I think the issue is that schema does not layer the same 
>way as, say UML, in that classes can be members of themselves and 
>one can take a subproperty of subPropertyOf or rdf:type.
>
>I think we need to clearly articulate the advantages of the design 
>choice that has been made.

I disagree. first, we did not make it, it was imposed by our charter. 
Second, the only objection to it from this comment can be succinctly 
phrased as "I don't like that way of doing it" which does't really 
need to be dignified with a careful answer, particularly in view of 
the fact that when asked for clarification, the commentor's response 
was somewhere between unhelpful and downright rude.

>
>I suggest the following reason for the design choice and why we 
>should not change.  I welcome comments and other suggestions:
>
>1) RDFS is designed to be a lower layer for the semantic web stack 
>that is extended by restriction.  All structure at this layer is 
>imposed on all higher layers.  A layered structure is not necessary 
>and the principle of minimal restriction suggests it should be 
>omitted.
>
>2) A further consideration is the cost of change at this point.  To 
>switch to a layered approach would require a massive rethink and 
>would affect not only the RDFCore specs but also OWL.  Only a show 
>stopping problem with the current design could justify the cost of 
>such a change.
>
>We note that it is possible to build more strictly layered languages 
>on top of RDF(S), Owl DL/Lite being examples.

That might be well worth articulating in more detail. I think we 
could do a fairly exact job on this which a lot of people would find 
helpful.  Since Jeremy has already done the donkey work for this in 
defining how to tell if an OWL-RDf graph is in OWL-DL ( which is 
precisely the 'layered' subset of OWL in this sense), we should be 
able to easily adapt his algorithm to define a 'layered style' of 
writing RDF and put it in an appendix somewhere. I am willing to 
tackle writing a draft of this.  It would be relevant to vass-01, 
pan-01 and Qu-03.

Pat
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Received on Tuesday, 27 May 2003 17:19:53 EDT

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