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RE: requirement: rdfs query (for lack of a better name...)

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Fri, 7 May 2004 21:29:42 +0100
To: "'Pat Hayes'" <phayes@ihmc.us>, "'Kendall Clark'" <kendall@monkeyfist.com>
Cc: "'RDF Data Access Working Group'" <public-rdf-dawg@w3.org>
Message-ID: <000301c43472$096b9ca0$0a01a8c0@atlas>



-------- Original Message --------
> From: public-rdf-dawg-request@w3.org <>
> Date: 07 May 2004 18:36
> 
> > On Thu, May 06, 2004 at 12:10:56PM -0700, Rob Shearer wrote:
> > >  I could on at great length about how bad an idea I think this is,
> > > but  I'll keep it short.
> > 
> > Uh... that's, well, less than ideal and not the least bit persuasive.
> > FWIW. 
> > 
> > >  Adding "just a little bit of inference" to the query language is
> > > the road to disaster. It just doesn't work that way.
> > 
> > Where in my requirement does it say "just a little bit of inference"?
> > Where does it imply it? I must have missed that bit. :>
> > 
> > And, besides, charter thwack:
> > 
> >   1.8 Derived Graphs
> > 
> >   The working group must recognize that RDF graphs are often
> >   constructed by aggregation from multiple sources and through logical
> >   inference, and that sometimes the graphs are never
> >   materialized. Such graphs may be arbitrarily large or infinite.
> > 
> > >  What's more, adding support for just one particular flavor of
> > > supplementary semantic knowledge (RDFS) is great way to kill off use
> > > of  any other knowledge sources.
> > 
> > Uh... RDFS is hardly "one particular flavor of supplementary semantic
> > knowledge". That's about as perverse a description as I can imagine.
> 
> Why? Seems to me to be exactly on the mark.
> 
> > Besides, if you're worried about "killing off" OWL, that's an argument
> > to do RDFS in 1.0 and OWL in 2.0, not an argument not to do RDFS at
> > all.
> 
> The point is, if we allow inference, where do we stop? Why not stick
> to retrieving actual RDF, keep it as small and fast as possible, and
> leave inference to inference engines downstream of the actual query.
> Seems to me that querying is one thing, inference another.

Agreed - queries execute against RDF graphs.

It is a thing that looks like an RDF Graph to the query request and might be
implemented by storage, inference, custom rules, something else, without
that being of concern or visible to the client making the query - that's
your downstream right?

> 
> BUt if we must involve inference, let me suggest a methodological
> strategy: we treat it as 'direct' retrieval from a virtual graph
> which is an appropriate inferential 'closure' (eg under transitivity
> of subClassOf). This keeps the discussion clean since we can
> distinguish retrieval-from-graph issues separate from
> which-graph-retrieved-from issues, and it helps keep inference
> strategy issues out of the way. It also BTW gives engine designers more
> leeway. 
> 
> Pat
Received on Friday, 7 May 2004 16:31:18 GMT

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