- From: tim finin <finin@cs.umbc.edu>
- Date: Mon, 05 Mar 2001 22:47:14 -0500
- To: Tim Berners-Lee <timbl@w3.org>
- CC: "Sigfrid Lundberg, Lub NetLab" <siglun@gungner.lub.lu.se>, Peter Crowther <Peter.Crowther@melandra.com>, pat hayes <phayes@ai.uwf.edu>, www-rdf-logic@w3.org
Tim Berners-Lee wrote: > I think we all agree that < and <= style of subProperty are both consistent > reasonable terms. > ... > 1. Saying that subclassOf(c,d) is a way of saying forall x, in(x,c) => > in(x,d) which is a simple thing to say. Lots of rules systems allow that to be > expressed. > > Saying properSubClassOf(c,d) is to say > forall x. in(x,c) => in(x,d) and exists y. in(x,d) and not(in(x,c)) > This is a more complicated thing to say, as it uses a "not". If we take c and d to be intensional descriptions then wouldn't it be better to say that it means possible((Ey) in(y,d)^not(in(y,c)))? The car example would then be ok as long as it was logically possible for the Robin company to make something with other than three wheels. -- Tim Finin, Prof Computer Science & Elect Eng, Director Inst. for Global Electronic Commerce, Univ of Maryland Baltimore Cty, 1000 Hilltop, Baltimore MD 21250. 410-455-3522 fax:-3969 finin@umbc.edu http://umbc.edu/~finin/
Received on Monday, 5 March 2001 22:46:34 UTC