Re: Little question for RDM theoristes
Date: 16 Jun 2006 06:45:12 -0700
Message-ID: <1150465512.937028.262320_at_u72g2000cwu.googlegroups.com>
Erwin a écrit :
> > Your question implies relations = relvalues...which if I follow this
Considering you confuse relvalues and relations and seem to persist...I
am doubtful the rest of the comments will be any useful but I will
take time to respond one last time....
> This question is not irrelevant at all since the heading is regarded as
What do you mean *regarded* as a definition type...Can't you think
about the consequences of doing that?
If you consider header metadata as a part of relation type deifnition,
you include human interpretation in the definition of the
relation....RM only bridges the gap between formal representation of
relations and human interpretation...human interpretation should be
done as a last step not as primary step...Totally contradicts the
purpose of RM.
header has been included in formal definitions only to help poor SQL
> > false premise reasonning would lead to relations that have similar
> > relvalues being equal which is totally false...2 relvar with same
> > relvalues are NOT necessarily equal.
>
> TTM Chapter 4, RM prescription 10 :
>
> "A relation value (relation for short) ..."
>
> Therefore at least to Chris Date, 'relations=relvalues' is most
> certainly true. I'd say that's a strong indication of just how much
> "false premise" there is within.
>
> > This question is totally irrelevant if you consider a relation as being
> > equal to a relvalue...
> the definition of the applicable relation type. And for values to be
> equal, they must most certainly be of the exact same type, inheritance
> issues notwithstanding of course