Re: [RIF] Reaction to the proposal by Boley, Kifer et al

I'm not sure what exactly is entailed by first-class citizenship of 
RDF/OWL in RIF.  Oracle has a small but growing number of customers who 
are adopting Semantic Web technologies, e.g. in the life sciences area.  
We don't object to meeting their needs.  On the other hand, the majority 
of our customers and developers are using non-semantic web technologies 
such as web services, BPEL, XQuery, XmlSchema, XSLT, etc. combined with 
Java and SQL, to build their applications.  We cannot require them to 
adopt RDF or OWL in order to use RIF.  Therefore, XML data must be 
supported by RIF, and RIF must be fully functional for the case where 
only XML data is used.

Alex Kozlenkov wrote:

>Guys
>
>There are a few general concerns we have about the points raised by
>Peter in that RDF/OWL should be first-class citizens in RIF. Firstly,
>the production/reaction rules should play a good part of the standard.
>As I understand it, it has been an industrial requirement all along,
>certainly from our company. PR/RR have their own semantics that is not
>directly compatible with, say, RDF deduction.
>
>Secondly, tying RIF closely to OWL would effectively assume that
>well-designed OWL ontologies become a prerequisite to do any meaningful
>form of inference. The reality of large software projects is that it may
>be prohibitively expensive to construct and maintain a consistent and
>complete set of reference ontologies even for a subset of the main line
>of business. In research, it may work well, while in the real world,
>only very stable parts of the business could be covered while other more
>volatile parts may stay outside of the OWL glasswork. What I am saying
>is that rules may have to play a pragmatic role than other parts of the
>Semantic Web technologies hence tying them closely with these parts may
>hinder the success of the rules technologies per se. Bad ontologies can
>unfortunately also be easily constructed and what about reasoning in
>their presence, I'm worried about how the system will behave in this
>case.
>
>I was wondering if you think these two observations are making sense.
>
>Alex Kozlenkov
>
>Advanced Technologies Group
>Betfair Ltd.
>
>-----Original Message-----
>From: public-rif-wg-request@w3.org [mailto:public-rif-wg-request@w3.org]
>On Behalf Of Peter F. Patel-Schneider
>Sent: 03 May 2006 12:27
>To: kifer@cs.sunysb.edu
>Cc: public-rif-wg@w3.org
>Subject: Re: [RIF] Reaction to the proposal by Boley, Kifer et al 
>
>
>From: Michael Kifer <kifer@cs.sunysb.edu>
>Subject: Re: [RIF] Reaction to the proposal by Boley, Kifer et al 
>Date: Wed, 03 May 2006 01:35:08 -0400
>
>  
>
>>"Peter F. Patel-Schneider" <pfps@inf.unibz.it> wrote:
>>    
>>
>>>I, on the other hand, have some serious concerns with the proposal.
>>>      
>>>
>
>  
>
>>>I worry about using a substitution in the basis of the semantics of
>>>conditions, in particular because the rest of the semantics of
>>>      
>>>
>conditionals
>  
>
>>>(including the semantics of existentials) are unspecified in the
>>>      
>>>
>proposal.
>  
>
>>>Will this actually end up close to a known logic?
>>>      
>>>
>>This is based on a known logic: infinite Herbrand interpretations.
>>    
>>
>
>Reference, please.
>
>  
>
>>It is easy to extend this semantics for general, non-Herbrand domains.
>>But this will be useful only for the FOL dialect. The others will have
>>    
>>
>to
>  
>
>>fall back on Herbrand interpretations.
>>    
>>
>
>I worry about situations like the following.  
>
>Suppose that there (only) are two constants, T and F, and (only) one
>one-place function, N.  Does it then follow from the following two facts
>
>	N(T) = F
>	N(F) = T
>
>that
>
>	Ax Ey x = N(y)
>
>
>[...]
>
>  
>
>>>I worry about the connection between the proposal and RDF and OWL.
>>>      
>>>
>I do
>  
>
>>>not view it as appropriate to relegate existing Semantic Web
>>>      
>>>
>languages to
>  
>
>>>an add-on query interface.
>>>      
>>>
>>Why?
>>    
>>
>
>Because we are supposed to be working within the confines of the
>Semantic Web.
>
>  
>
>>A query interface is a very general thing. 
>>    
>>
>
>Is it really?  It instead seems to me to be much more like a ghetto.  In
>particular, the proposal uses a ternary predicate for RDF triples,
>divorcing RDF facts like ex:a rdf:type ex:b from a representation
>as ex:b(ex:a).
>
>  
>
>>It can range from seamless
>>integration (e.g., in FOL-based dialects) 
>>    
>>
>
>How?  Can a query interface actually achieve complete integration?  For
>example, can a query interface reasonably support a rule language that
>is
>oblivious to the source of information, i.e., what sort of rule could be
>used to produce the transitive closure of the binary relation R, where
>some
>facts about R are in RDF and others are in the form of conditionless
>rules?
>
>  
>
>>to Rosati and Eiter et al. style integration, 
>>    
>>
>
>Perhaps.  These sorts of integrations do make a firm divide between
>"rule"
>predicates and other predicates, so it may be more natural to "query"
>the
>other predicates.  I am not totally convinced, even in this case.  I
>note
>that the papers by Rosati et al. do not have a special query interface
>for
>the other predicates.
>
>  
>
>>to external calls to ontologies. 
>>    
>>
>
>Well, I suppose that if the ontology cannot be changed then there is no
>problem with a query interface.
>
>  
>
>>Different degrees of
>>integration will be appropriate for different dialects. (For instance,
>>    
>>
>what
>  
>
>>would be the appropriate integration for PR rules?)
>>    
>>
>
>Good question.  What answers are reasonable in this proposal? 
>
>  
>
>>	--michael  
>>    
>>
>
>Peter F. Patel-Schneider
>
>
>
>
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Received on Wednesday, 3 May 2006 18:29:44 UTC