- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Wed, 11 Apr 2007 19:40:12 +0100
- To: <conrad.bock@nist.gov>
- Cc: Evren Sirin <evren@clarkparsia.com>, Owl Dev <public-owl-dev@w3.org>, Evan Wallace <evan.wallace@nist.gov>, Yevgeny Kazakov <ykazakov@cs.man.ac.uk>
On 11 Apr 2007, at 18:54, Conrad Bock wrote: > > Evren, > >>> Was wondering if anyone is looking into whether this fragment can >>> be added tractably to OWL DL (1.0): > >>> (forall (x y z) >>> (if (and (P x y) >>> (R x z)) >>> (S y z))) >>> >>> For example, the uncles of my children include all my brothers >>> (P=children, R=brothers, S=uncles). > >> You can turn the antecedent into a property chain using the >> inverse of P >> and then use the standard complex role inclusions of OWL 1.1 as: > >> SubObjectPropertyOf(SubObjectPropertyChain(InverseObjectPrope >> rty(children) >> brothers) uncles) > > Great, thanks. > >> provided that the restrictions described at [1] are not violated. > > Do you happen to know if anyone has shown these to be the maximal > restrictions, ie, any loosening of them will cause undecidability? In > particular, is the regularity restriction maximal? Yevgeny Kazakov has done some work on this. He has shown that the restriction is not maximal (which is pretty obvious), and I believe that he has devised an alternative and strictly more general restriction. I have a feeling that there is even an undecidability result related to maximality, but I might have imagined that :-). Yevgeny can no doubt tell you more. Regards, Ian > > Conrad > > > PS: I assume the first set of bullets are disjunctive, but the text > doesn't say this explicitly. > > >
Received on Wednesday, 11 April 2007 18:40:25 UTC