Re: [ontolog-forum] Data, Silos, Interoperability, and Agility

[Michael Brunnbauer <brunni@xxxxxxxxxxxx>]

Hello John,    (01)

On Wed, Sep 25, 2013 at 12:42:37PM -0400, John F Sowa wrote:
> > SPARQL 1.0 has the expressive power of Relational Algebra, and therefore of
> > FOL: http://www.dcc.uchile.cl/cgutierr/ftp/expressive-power-sparql.pdf
> >
> > So what is the point of your statement that SQL WHERE is as expressive as 
>FOL ?
> 
> Yes, but...  The first "but" is that SQL, for all its problems, is a far
> simpler way to express FOL than SPARQL.    (02)

My experience tells me that SPARQL queries get complicated quickly - especially
if disjunctions are involved - so I think you are right.    (03)

> The DAML project could and should have adopted Datalog as their query
> language.    (04)

But not because of its expressivity but because of its syntax. Much more
interesting than the expressivity of the query language is the expressivity
of what is queried - as Ed already pointed out.    (05)

The combination of a OWL reasoner and SPARQL is much more powerful than a
SQL database. But you seem to prefer Datalog also as logic.    (06)

I wonder if Datalog is really more powerful than OWL DL as both are decidable ?    (07)

Regarding your undecidability mantra, why don't you go for OWL Full instead,
which seems to be undecidable ?    (08)

BTW: Do you know the quote from timbl in this Wikipedia article:    (09)

 http://en.wikipedia.org/wiki/Rule_of_least_power    (010)

So they went for DL because FOL "cannot be analyzed" ?    (011)

Regards,    (012)

Michael Brunnbauer    (013)

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