From: Ian Horrocks (horrocks@cs.man.ac.uk)
Date: 03/01/01
On March 1, Jim Hendler writes: > At 12:11 PM -0500 3/1/01, Mike Dean wrote: > >DAML+OIL currently supports TransitiveProperty and > >inverseOf. Should we also be able to indicate a > >SymmetricProperty > > > > P(a, b) implies P(b, a) > > > >such as sibling or spouse? > > > >I checked and see that OIL [1] supports this. > > > >How about ReflexiveProperty > > > > P(x, x) > > > >such as equivalentTo? > > > >I'm told that TransitiveProperty and SymmetricProperty and > >ReflexiveProperty would imply samePropertyAs (equivalence). > > > >Comments? > > > > Mike > > > >[1] http://www.ontoknowledge.org/oil/rdf-schema/2000/11/10-oil-standard > > we originally let this stuff out of DAML with a note to "improve it > later" - has the time come to do that? Might also be worth > considering whether there are other levels of this (transitive > closure, for example) that we might want to consider - > i.e. > Driveable(X Y) is the transitive closure of Landborder(X Z) Transitive closure would also be a real extension to the expressive power of the language. Although the extension wouldn't change the complexity class of the language, there is good evidence to suggest that empirical tractability would be seriously damaged by adding transitive closure. Ian
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