Chris, (01)
Sorry, I misspoke. I meant the typing of OWL DL. (02)
CM> ... I don't know of any division of RDF(S) into typed
> and untyped versions. Moreover, the semantics of RDF
> is extraordinarily weak, and comes nowhere close to the
> expressiveness of Codd's relational calculus (as I'm
> sure you know); it can't even handle >2-place relations
> (except in a limited and kludgy way). (03)
That is certainly true. (04)
JS>> ... But for performance, reliability, security, etc.,
>> RDF & OWL are still infants compared to RDBs, which run
>> the world economy, both now and for a long time to come. (05)
CM> This is apples and oranges, isn't it? Talking about
> reliability and security, and maybe even performance, with
> respect to RDF/OWL is a lot like talking about them wrt,
> say, Peano Arithmetic. (06)
I agree that expressivity depends on the logic of the SQL
WHERE-clause vs the logic of RDF/OWL. But when we are
talking about which platform to choose for an application, (07)
the surrounding support system becomes a major issue. (08)
CM> RDF and OWL are theories in a certain language designed
> to exploit the infrastructure of the web and, in the case
> of OWL DL, the decidability of certain description logics. (09)
Other than the choice of an XML-based syntax, there's nothing
about RDF and OWL that makes them any better suited to the WWW
than SQL. All the major vendors have integrated their RDB
systems into the web servers, and they support SQL queries
over data represented in web pages. (010)
Even vendors that support the option of using either XPath
or SQL for queries of XML data find that many of the users
prefer to state their queries in SQL. That is more likely
to be an issue of expressivity and ease of use. (011)
CM> Reliability and security, and to a certain extent,
> performance, are orthogonal issues. (012)
I agree that they are independent of the expressivity of the
core logic, but they are central to the issue of which system
to choose for an application. (013)
Chris Menzel (014)
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