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Re: Reminder: pending discussion "membership" (pending discussion on ACTION-350)

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Fri, 07 Dec 2007 10:14:26 -0500
To: Dave Reynolds <der@hplb.hpl.hp.com>
Cc: axel@polleres.net, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
Message-ID: <2605.1197040466@cs.sunysb.edu>


Dave Reynolds <der@hplb.hpl.hp.com>:
>
> I am convinced that including these primitives moves RIF from the domain 
> of rule interchange into that of data model interchange. Had that been 
> explicitly part of the RIF charter I am not certain we would have 
> approved the formation of RIF.

Dave,
It looks to me that your objections are political rather than technical.
I do not have technical arguments to counter that.

	--michael  


> Michael Kifer wrote:
> > CSMA had an action to bug me about the ## feature :-)
> > I thought that others might also be interested, so I am including my
> > arguments below.
> > 
> > First, one needs to be able to specify that one class is a subclass of
> > another class **as part of the KB**.
> 
> I disagree, at least if by KB you mean RIF rules rather than RIF rules + 
> externally specified ontology or data model.
> 
> Expressing data models or ontological models and any subClass relations 
> associated with them is not a RIF requirement.
> 
> > For instance, 
> > 
> > student##person.
> > father(person)##person.
> > 
> > In KB apps this is used for reasoning, not just as part of a data
> > model. How would one specify this info otherwise?
> 
> Using your data modelling language of choice. In the case of the 
> Semantic Web stack, of which RIF is a part, the answer is RDFS/OWL.
> 
> In the case of XML Schema models then complex types can be related by 
> both extension and restriction in ways that don't neatly map to subClass.
> 
> > Here is a more sophisticated example: parametrised lists.
> > 
> > list(?Subclass) ## list(?Super) :- ?Subclass ## ?Super.
> > 
> > (List of FOOs is a subclass of lists of BARs if FOO is a subclass of
> > BAR. We could have list(father(person)), for example.)
> > 
> > RDF's subclassOf does not cut it because
> > 
> > 1. It imposes additional axioms, which are not commonly accepted.
> > 2. It is also not even defined for classes specified using function terms
> >    (like list(?Foo)).
> > 
> > Both arguments are also applicable to the RDF membership relationship.
> > 
> > I am convinced that throwing out these primitives serves no purpose and
> > will just gratuitously cripple the BLD.
> 
> I am convinced that including these primitives moves RIF from the domain 
> of rule interchange into that of data model interchange. Had that been 
> explicitly part of the RIF charter I am not certain we would have 
> approved the formation of RIF.
> 
> Dave
> -- 
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> 
Received on Friday, 7 December 2007 15:14:55 GMT

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