Hi Chimezie --
Thanks for your most helpful posting.
At 01:00 PM 8/22/2006 -0400, you wrote:
Actually, I believe by virtue of being of the SHOIN family of Description
Logics [1] that OWL-DL & RDFS can express this [transitive over] through
role hierachies and transitive roles
So, does it remain true that OWL by itself, without the help of RDFS,
cannot express "transitive over" ?
(both of which are part of [2] SHOIN: S - Role transitivity, H - Role
hierarchy)
[1] http://www.cs.man.ac.uk/~horrocks/Publications/download/2003/HoPH03a.pdf
[2] http://www.cs.man.ac.uk/~ezolin/logic/complexity.html
I.e., instead of
:worksFor :transitiveOver :consistsOf.
you would have
:consistsOf rdf:type owl:TransitiveProperty
:worksFor rdfs:subPropertyOf :consistsOf
Which would result in the same conclusions via a reasoner
I'd like to try this in practice. Can you suggest some reasoners?
following the axiomatic semantics of owl:TransitiveProperty and
rdfs:subPropertyOf (in N3):
{?P a owl:TransitiveProperty. ?X ?P ?O. ?S ?P ?X} => {?S ?P ?O}.
{?P rdfs:subPropertyOf ?R. ?S ?P ?O} => {?S ?R ?O}.
I hope to see this working. But even if it does, I'm concerned that
extending this kind of notation beyond toy problems is going to result in
reasoning that is very hard to check. To put it another way, the logic is
very powerful, and the notation is somewhat opaque, so that a small slip in
writing is easy to make and could have vast erroneous consequences --
particularly if deployed over the world wide web.
Hope I'm wrong about this. What do you think?
Cheers, -- Adrian
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