- From: Dan Connolly <connolly@w3.org>
- Date: 02 Jan 2003 15:54:57 -0600
- To: Ziv Hellman <ziv@unicorn.com>
- Cc: Jim Hendler <hendler@cs.umd.edu>, Jeff Heflin <heflin@cse.lehigh.edu>, "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>, www-webont-wg@w3.org
On Thu, 2003-01-02 at 13:34, Ziv Hellman wrote: > My two sense: > > 1. Classes in OWL _ARE NOT_ the same as sets, Hmm... if I write YES, THEY ARE, does it convince you? i.e. please explain why you think owl:Classes are not the same as sets. (I know that rdfs:Classes are different.) Please provide an example of two owl classes that have the same members but differ in some other property; i.e. some ?C1, ?C2, ?P, and ?X such that ?C1 a owl:Class. ?C2 a owl:Class. ?C1 rdfs:subClassOf ?C2. ?C2 rdfs:subClassOf ?C1. ?C1 ?P ?X but not ?C2 ?P ?X. > as the word is generally defined and used in mathematics, > so it would be disastrously wrong to change owl:class to owl:set > -- this distinction ought to be kept clear to the general public. > > 2. The matter of how misleading sameClassAs can be as mentioned > below is indeed tricky, because it exactly highlights the > intensional/extensional distinction -- thinking of intension > and extension as two functions on the class of classes, we mean > by sameClassAs that the two items have different values from the > perspective of the intension function, What's the intension function? I don't think this line of argument helps me much. I'm trying to get a strictly formal understanding. > but the same value from the > perspective of the extension function, so owl:sameExtensionAs is > more precise. But is it really requiring too much understanding > of logic to use that name when at the same time we expect users > to grok intensional and extensional distinctions if they are going > to use full OWL correctly? sameMembersAs seems intuitive and correct. -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 2 January 2003 16:54:45 UTC