Re: Principle of Orthogonal Design
Date: Mon, 28 Jan 2008 02:58:56 -0800 (PST)
Message-ID: <0a872b75-448e-4131-ba5b-6bcee88da815_at_e10g2000prf.googlegroups.com>
On 28 jan, 02:12, mAsterdam <mAster..._at_vrijdag.org> wrote:
> Jan Hidders wrote:
> > mAsterdam wrote something very much like:
> >> Pragmatical redefinitions must be temporary and tracked.
> > Sure, we agree on that.
>
> <unsnip>
>
> Wether the relation between heading and tuples goes
> via names or ordering is relevant or not.
>
> If it is not I want it out of scope.
>
> </unsnip>
> >> DEFINITION: Two relations R and S are said to have dependency-induced
> >> overlap if there is a dependency that requires that sometimes some
> >> tuples(1) of R are also in S.
>
> >> (1) for some definition of tuples that allows restricted
> >> reshuffling of its values. To do.
>
> > The only way to achieve (1) so that it also takes all normal inclusion
> > dependencies into account is to define tuples as something equivalent
> > to bags of values.
>
> Nice, a third alternative way to state the same relation.
> How can this be relevant?
> > Such an operation on its internal organs is going
> > to change the relational model beyond recognition.
>
> This is hardly surprising when part of the (database local)
> definition of relation is under discussion. More specifically:
> How do tuples conform to relation headers?
> > I'm going to
> > strongly insist that we stick to the classical definitions of the
> > named perspective and state in the definition that we are talking
> > about inclusion up to relabeling:
>
> > DEFINITION: Two relations R and S are said to have dependency-induced
> > overlap if there is a dependency that requires that sometimes some
> > tuples of R are also in S after renaming the attribute names.
>
> Two glossary todo items: [Trivial](new) and [Type].
> The s/meaning overlap/dependency induced overlap/
> did help to clarify.
>
> This time 'type' is the label on a jar containing something else.
> Which 'classical definitions of the named perspective' do you mean?
As in the Alice book. Pretty much *the* authority in the area of database theory.
> Do you have a suggestion for
> s/type/$some_name_dependent_notion_similar_to_but_not_the_same_as_type/
> in PoOD related discussions ?
- Jan Hidders