[RDF] Re: Aside - Re: Question: DAML cardinality restrictions

[Jonas Liljegren]

Peter Crowther <Peter.Crowther@melandra.com> writes:

> > From: Jan Grant [mailto:Jan.Grant@bristol.ac.uk]
> >
> > I can't help feeling a little worried by these examples. Yes, I know
> > they're "only" examples. But the model of the world they present is
> > broken - will DAML be good for describing the real world or just
> > mathematical arenas and EDI? Is it even wise to try the former - or
> > should the examples be rewritten to be less contentious?

I look at the schema as a view on what is normal.  The real world is
modeld as nodes and arcs and must not follow any specific schema.  For
me (in Wraf [1]), the schema will serve as a template for requesting
information.

The schema forms the expectation of what to find.  A larger service
(in the semantic web) will probably have numerous conflicting
schemas.  That is a reflection of our own conflicting views on the
reality.

A service could maby jump from schema to schema, using the one that
best fit the current needs.

RDF was built to accept exceptions.  If some data goes beyond a
specific schema, a service could perform an analysis and maby request
help (from agents or users) to resolv the situation.  That could
result in additional statings saying that this is a known
contradiction, or maby by adding another rule explaining the
situation.


> A second problem, especially for concrete datatypes, is the unit problem.
> What do you measure shoe size in?  Inches?  Abstract units (see below)?  Is
> that speed in miles per hour, kilometres per hour, metres per second, or
> furlongs per fortnight?  So a second source of contention is from
> underspecified examples; this can be reduced by being more explicit about
> your units, but I don't see anything in XML Schema that aids this [a pet
> peeve of mine].

Yes. Units should be part of the RDF handling of datatypes.  The RDF
spec gives an suggestion on how to do that.  That unit could also be
infered by various rules.




[1] http://www.uxn.nu/wraf/

-- 
/ Jonas Liljegren

The Wraf project http://www.uxn.nu/wraf/
Sponsored by http://www.rit.se/