Re: TEST: 6 of 7: empty universe example,

From: Jim Hendler <>
Subject: Re: TEST: 6 of 7: empty universe example,
Date: Thu, 24 Jul 2003 09:35:51 -0400

> At 12:59 PM +0300 7/24/03, Jeremy Carroll wrote:
> >Mehrdad:
> >>  In OWL-DL (as in FOL), the universe of the interpretation is always
> >>  required to be a non-empty set.
> >
> >
> >that was true in the LC documents; however a careful reeading of the current
> >editors draft of the direct semantics does not indicate that the
> >interpretation of owl:Thing must be non-empty.
> >
> >Jeremy
> I'm pretty agnostic on this one, but is there some benefit to 
> allowing this odd case - hard for me to believe it will ever come up 
> in practice, and it does seem to be confusing people -- Peter, why 
> the change?
>   -JH

Well, the change came about somewhat by accident, when the extra domain
elements were added to handle annotations on 5 June.  This had the
unintended side effect of fixing an unnoticed bug where the direct
semantics assumed a non-empty universe of OWL individuals, but the
RDFS-compatible semantics did not.  I only noticed the full effects of the
change when Jeremy asked his questions about the empty universe example.


Received on Thursday, 24 July 2003 10:25:43 UTC