Re: Interpretation of RDF reification

Adrian,
Thanks, I have followed the links briefly and would like to spend more time
on it over the course of this week.
Adam

On 26/03/06, Adrian Walker <adrianw@snet.net> wrote:
>
> Adam -
>
> Just to take up two of the many good points in your very thoughtful
> posting:
>
> At 09:55 PM 3/26/2006 +0100, you wrote:
> >Is the issue that were a more expressive language used, there would be
> >more in the user community at work on schema, data and queries utilising
> >that language?
>
> If we try writing a small practical application as reasoning over RDF, we
> see that the proof chains quickly descend into details that are
> uninteresting and opaque to an end user.  To see this, try running the
> example called RDFQueryLangComparison1, by pointing a browser to
> reengineeringllc.com, and ask for an explanation of the answer
>
> "Jeen Broekstra  is an author , with email jbroeks@cs.vu.nl , of  'An
> Overview of RDF Query Languages'".
>
> Bear in mind that this is a simple academic example.
>
> Now, one could argue that proofs and explanations are anyway not of
> interest to end users of real applications. I've heard this expressed as
> "We don't want Generals reading program traces".  A counter argument comes
> from the fact that a small change in a logical specification can have huge
> consequences, particularly if the reasoning is done over the web.  So, we
> need to be able to present human-understandable proofs at least to
> analysts, and probably sometimes also to end users.
>
> > Is there a particular application that would show the difference between
> the two languages
> > and prove a compelling case for would be adopters?
>
> There are actually quite simple looking examples that cannot be computed
> in
> OWL.  I believe that "transitive over" is one such
>
> (See http://www.reengineeringllc.com/demo_agents/TransitiveOver1.agent )
>
> There are at least two issues here though.  One is, can a practical
> application be computed at all in a particular language.  Another is, will
> the process by which results are obtained be transparent and
> understandable
> at the end user level.  For example, compare writing the example in the
> paper
>
>
> www.reengineeringllc.com/Oil_Industry_Supply_Chain_by_Kowalski_and_Walker.pdf
>
> (a) as rules in executable English, and  (b) as SQL.  Both are shown in
> the
> paper.
>
> It's clear from the example that there is no hope of scaling up to writing
> a practical, maintainable, understandable application directly in
> SQL.  It's likely that the same difficulty would arise with SPARQL, given
> the similarities with SQL.
>
> Bottom line -- for practical applications, we need sophisticated
> inferencing and explanation  tools (and IMHO also some lightweight NLP) on
> top of languages such as RDF, OWL, and SPARQL.   The "Semantic Web Layer
> Cake" can be viewed as pointing in this direction.
>
> Hope this makes sense.  Thanks in advance for comments.
>
>                                             -- Adrian
>
>
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