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RE: Issue jsr-118 (global datatyping)

From: <Patrick.Stickler@nokia.com>
Date: Fri, 4 Apr 2003 17:34:37 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B01B90C82@trebe006.europe.nokia.com>
To: <fmanola@mitre.org>
Cc: <gk@ninebynine.org>, <w3c-rdfcore-wg@w3.org>, <Art.Barstow@nokia.com>



> -----Original Message-----
> From: ext Frank Manola [mailto:fmanola@mitre.org]
> Sent: 04 April, 2003 17:48
> To: Stickler Patrick (NMP/Tampere)
> Cc: gk@ninebynine.org; w3c-rdfcore-wg@w3.org; Barstow Art (NMP/Boston)
> Subject: Re: Issue jsr-118 (global datatyping)
> 
> 
> Patrick--
> 
> I believe that "non-monotonicity" is more correctly used to describe 
> what goes on within the *same* reasoner, not between *different* 
> reasoners.  

Hmmm. OK. I wasn't aware of that.

> I'm not disagreeing with the idea that there will be 
> interoperability problems introduced whenever two systems disagree on 
> basic assumptions (in this case, whether the interpretation of the 
> properties affects the interpretation of the literals).

OK. Whatever you want to call it, inconsistency in the interpretation
of RDF statements by different systems or layers is IMO a bad thing
and should be guarded against.

But it seems we agree on that point.

Patrick


> Patrick.Stickler@nokia.com wrote:
> 
> > 
> > 
> >>-----Original Message-----
> >>From: ext Frank Manola [mailto:fmanola@mitre.org]
> >>Sent: 03 April, 2003 16:52
> >>To: Stickler Patrick (NMP/Tampere)
> >>Cc: gk@ninebynine.org; w3c-rdfcore-wg@w3.org
> >>Subject: Re: Issue jsr-118 (global datatyping)
> >>
> >>
> >>Patrick.Stickler@nokia.com wrote:
> >>
> >>
> >>>Er... you're telling them to use plain literals in the RDF but
> >>>interpret them as typed literals by the applications. This
> >>>means that conclusions drawn from an RDF-only application about
> >>>those CC/PP statements will differ from conclusions drawn by
> >>>a CC/PP application.
> >>>
> >>
> >>Yes.
> >>
> >>
> >>
> >>>That means that non-monotonicity is being introduced between the
> >>>RDF and CC/PP layers.
> >>>
> >>>No?
> >>>
> >>
> >>No.  Dealing with literals this way in CC/PP may be a Bad 
> >>Thing (e.g., 
> >>it may create a lack of interoperable semantics with other 
> >>applications), but I don't think it's properly described as 
> >>non-monotonicity.  It's always going to be the case that an 
> app that 
> >>uses a specialized vocabulary with built-in meaning that it 
> >>understands 
> >>is going to be able to draw more conclusions about graphs 
> using that 
> >>vocaulary than an RDF-only application.  This is true of OWL, for 
> >>example.  This doesn't mean OWL is introducing 
> >>non-monotonicity between 
> >>the RDF and OWL layers.  The same is true for specialized 
> >>interpretations of schemas and literals (it's an 
> application specific 
> >>way of interpreting the RDF, just as a specialized vocabulary 
> >>would be). 
> >>  We can still claim it's a bad idea without describing it as 
> >>non-monotonicity.
> >>
> >>
> > 
> > It's one thing to have vocabulary that will not be understood at
> > lower levels, or for which there will be inferences that can be
> > made at a higher level that do not hold at the lower levels.
> > 
> > It's another issue to have different inferences at different
> > levels based on the very same statements.
> > 
> > If my RDF-only application holds the following entailment:
> > 
> > IF
> >    _:x ccpp:BitsPerPixel "2" .
> >    _:x ccpp:Model "2" .
> > THEN
> >    _:x ccpp:BitsPerPixel _:v .
> >    _:x ccpp:Model _:v .
> > 
> > yet if for my CC/PP application, that entailment does *not* hold, 
> > then that is non-monotonicity, and that is completely unnacceptable.
> 
> 
> I don't agree.  It would be non-monotonic if additional triples were 
> added to the graph, and the *RDF-only application* then 
> determined that 
> the entailment no longer held.  However, what we have here is a 
> different reasoner, the CC/PP application, making different 
> assumptions 
> about how to interpret the literals (namely that the 
> properties provide 
> additional information).  The CC/PP application can consistently 
> interpet those literals based on those assumptions.  
> Admittedly that may 
> creates problem for interoperation between the two applications;  all 
> I'm saying is that I doubt "non-monotonicity" is the way to 
> describe this.
> 
> 
> > 
> > Compare to
> > 
> >    _:x ccpp:BitsPerPixel "2"^^ccpp:Number .
> >    _:x ccpp:Model "2"^^ccpp:Literal .
> > 
> > which does not entail
> > 
> >    _:x ccpp:BitsPerPixel _:v .
> >    _:x ccpp:Model _:v .
> > 
> > And note that I have not used any vocabulary but the CC/PP 
> vocabulary.
> > 
> > The proposal promotes non-monotonicity.
> > 
> > We should recommend to CC/PP that they adopt typed literals 
> in their 
> > serializations since the CC/PP semantics clearly deals with datatype
> > values.
> > 
> > CC/PP knowledge about terminals is only one subset of 
> knowledge about
> > terminals, and that knowledge should have a consistent 
> interpretation
> > both by CC/PP specific applications as well as arbitrary 
> RDF applications
> > consuming that knowledge.
> 
> 
> Ideally this would be true (for any kind of specific application, not 
> just CC/PP), but I doubt it's going to happen (and in any event, I 
> continue to think "non-monotonicity" isn't the issue).
> 
> 
> > 
> > As such, any non-monotonicity, or any other incompatibility between
> > CC/PP specific and RDF-general interpretations of CC/PP expressed
> > knowledge should be avoided.
> > 
> > Patrick
> 
> --Frank
> 
> -- 
> Frank Manola                   The MITRE Corporation
> 202 Burlington Road, MS A345   Bedford, MA 01730-1420
> mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
> 
> 
> 
Received on Friday, 4 April 2003 09:34:40 EST

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