- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Tue, 30 Apr 2002 11:16:45 -0400
- To: jjc@hplb.hpl.hp.com
- Cc: www-webont-wg@w3.org
From: "Jeremy Carroll" <jjc@hplb.hpl.hp.com> Subject: RE: DTTF: List Ontology test case Date: Mon, 29 Apr 2002 22:25:16 +0100 [...] > > Well, I don't think that you get want you need out of this sort of thing. > > In particular, making you are not capturing the fact that there > > can only be > > one daml:first and one daml:rest triple for any particular list head. In > > fact, you can't capture this at all in DAML+OIL or FOWL. > > > > Sorry I don't understand; you're going to have to spell it out for this > bear of little brain. > > > Suppose I replace daml by foo (a prefix for http://example.org/foo#) > (I am not sure whether you are saying my approach doesn't work because of > the self-reference - so I'll remove it). > > I can capture the nil-terminated list of cons cells semantics in daml can't > I? [Detail below] > (I note I can't capture the syntactic restriction because of the lack of > unique naming...) > > I guess I can't capture that the list has finite length. > > Does daml:List have to have that syntactic restiction or would a semantic > restriction like this suffice? The problem has to do with the status of knowledge bases that include something like _:l rdf:type daml:List . _:l daml:first ex:first . _:l daml:rest _:l1 . _:l1 daml:first ex:seconda . _:l1 daml:rest daml:nil . _:l daml:rest _:l2 . _:l2 daml:first ex:secondb . _:l2 daml:rest daml:nil . Is this legal DAML+OIL? It certainly doesn't *look* like legal DAML+OIL. Lists are supposed to be lists, not trees. However, using DAML+OIL cardinality restrictions does not make the above illegal, it just means that ex:seconda and ex:secondb have to have the same denotation. So, for DAML+OIL lists to behave as expected, there needs to be a *syntactic* restriction on them, not a *semantic* one, which is all that can be stated in DAML+OIL. peter
Received on Tuesday, 30 April 2002 11:18:17 UTC