Re: Little question for RDM theoristes
Date: 16 Jun 2006 02:06:21 -0700
Message-ID: <1150448781.639057.68880_at_g10g2000cwb.googlegroups.com>
Erwin wrote:
> U-gene wrote:
> > Two relations (relvalues) exists. These relations have different
> > headers (schemas). Are these relvalues the values of different types?
>
> Yes.
>
> > IMHO all relvalues have the same type
>
> Yes, too.
>
> > and the headers is just data. May
> > be it is special kind of data which is different from rel.bodies' data.
>
> No. The heading is not data. For if it were, one logical consequence
> would be that you would have to be able to "update" it (the header part
> of the data) in some way. But what does that do to a relation value ?
> What operators would do that sort of thing ? Would such an operator
> have side-effects on the relation body ? etc. etc.
> In their most recent edition of the Manifesto, Date/Darwen have a
> chapter on nonscalar type inheritance. I haven't read it that far yet,
> but I presume that their ideas are that any specific relation type is a
> subtype of some "generic" relation type. Therefore, each relation
> value is of more than one type at the same time : its most specific
> type RELATION{somespecificheading} and its generic type
> RELATION{nospecificheading}.
So you argument on "why header is not data" cannot be accepted by me. Received on Fri Jun 16 2006 - 11:06:21 CEST