- From: by way of <Michel.Klein@cs.vu.nl>
- Date: 2002年8月26日 12:11:36 -0400
- To: www-rdf-comments@w3.org
- Message-Id: <5.1.0.14.2.20020826121044.0c5fede8@127.0.0.1>
[freed from spam filter -rrs] Date: 2002年8月26日 11:45:29 -0400 (EDT) Message-ID: <3D6A4D99.1B64A3C1@cs.vu.nl> From: Michel Klein <Michel.Klein@cs.vu.nl> Organization: Vrije Universiteit - computer science To: Brian McBride <bwm@hplb.hpl.hp.com> CC: www-rdf-comments@w3.org, Jeen Broekstra <jbroeks@cs.vu.nl> Brian McBride wrote: > [[[ > Can an instance of the Property class have a subClassOf property? What does > this mean? > ]]] [...] > The wording of the formal resolution is a bit bare, so let me add a few > words of explanation. What this means is that a resource can be both a > class and a property. If it is a Class, the resource has a class extension > which is the set of members of the class. If it is a property, it has a > property extension which is the set of pairs related by the property. If > it is both a class and a property, then it has both a class extension and a > property extension. The distinction between a class and its extension, and > a property and its extension is a mathematical trick introduced to avoid > Russel's paradox when we allows classes to be members of themselves. As > you see, I hope, it also works nicely to enable a resource to be both a > property and a class. > > Please could you respond to this message, copying www-rdf-comments@w3.org > indicating whether this is an acceptable resolution of this issue. Clearly, the issue that we raised has been solved by the decision of the RDFCore WG, because we asked for a clarification of the meaning. It looks as a reasonable solution. However, we have some concerns about the effect this might have on tools: likely most of them will not expect that a resource can be a Class and Property at the same time. On the other hand, this is a situation that will probably not occur very often. Regards, Michel. (also on behalf of Jeen Broekstra) -- Michel Klein <>< | Faculty of Sciences | Vrije Universiteit phone: +31 20 444 7782 | De Boelelaan 1081a, room U3.50 http://www.cs.vu.nl/~mcaklein | 1081 HV Amsterdam, the Netherlands
Received on Monday, 26 August 2002 12:11:48 UTC