Re: Relation Schemata vs. Relation Variables
From: J M Davitt <jdavitt_at_aeneas.net>
Date: Wed, 06 Sep 2006 02:38:28 GMT
Message-ID: <EwqLg.84$MD6.80_at_tornado.ohiordc.rr.com>
>
>
> Ok, what on earth is a transition constraint then? A transition occurs
> when an 'entity' changes. In contrast a fact cannot 'change'. It is
> either true or not, and that is that.
>
> I conclude therefore that transitions are associated with entities
> alone, as are constraints upon them. The RM is unconcerned with
> 'entities' and hence is equally unconcerned with transition
> constraints.
>
> This whole question is therefore moot.
Date: Wed, 06 Sep 2006 02:38:28 GMT
Message-ID: <EwqLg.84$MD6.80_at_tornado.ohiordc.rr.com>
JOG wrote:
> Brian Selzer wrote:
>
>>[snip] >>This is a contradiction. A transition constraint must either be able to >>pair the elements of two relations for comparison or be given a set of pairs >>to compare.
>
>
> Ok, what on earth is a transition constraint then? A transition occurs
> when an 'entity' changes. In contrast a fact cannot 'change'. It is
> either true or not, and that is that.
>
> I conclude therefore that transitions are associated with entities
> alone, as are constraints upon them. The RM is unconcerned with
> 'entities' and hence is equally unconcerned with transition
> constraints.
>
> This whole question is therefore moot.
What he said.
> The rest of this argument is based on a confused assumption AFAICT.
That part, too. Received on Wed Sep 06 2006 - 04:38:28 CEST