Re: Relation Schemata vs. Relation Variables

vc wrote:
> Marshall wrote:
> [...]
> > The idea of transition constraints is inherrently non-set-theoretic,
> > because it assumes tuple-identity.
>
> How come ? One can easily think about a transition constraint in set
> terms by extending the original universe with a new attribute value.
> Then declarative TC specification would be no different from any other
> integrity constraint specification. That's, by the way, is what
> Dataphor does with its 'old' and 'new' values.

Please permit me to withdraw my above-quoted statement; upon further reflection, (derived from vc's comment) it does not hold up.

Marshall Received on Fri Aug 25 2006 - 19:03:04 CEST