Re: no names allowed, we serve types only

On Feb 17, 10:08 pm, Keith H Duggar <dug..._at_alum.mit.edu> wrote:
> On Feb 17, 7:21 pm, Tegiri Nenashi <tegirinena..._at_gmail.com> wrote:
>
> > On Feb 17, 3:46 pm, Tegiri Nenashi <tegirinena..._at_gmail.com> wrote:
> > > The thread started as Keith's attempt to demote attribute names in
> > > favor of types,
>
> Eliminate not just demote.
>
> > > and was vehemently objected to. From my angle (that
> > > would be relational lattice:-) Relational Model is a theory of
> > > Relations with Named Attributes. It is difficult to see unnamed
> > > perspective (with positional attributes) as contender anymore. This is
> > > especially evident through the prism of set intersection join (aka
> > > composition) operation...
>
> Except that I'm not proposing "positional attributes" so I fail
> to see the relevance of your point?

I was addressing Named perspective vs. Positional perspective p.31-33 in the Alice book.

> First, I'm asking a simple
> question: suppose we have already have unique types for every
> header then what theoretical capability do the names add? (Bob
> argues that they are necessary for "controlling" natural join.
> I disagree that they are /necessary/ for this; but my complete
> response to that will have to wait a few days.)

And, adding to Bob's point, there are many more [non-classic] relational operators that depend on the attribute naming.

The issue is more complex, though. The algebra with unnamed attributes (that is Algebra of Binary Relations) is arguably much more established construction in math. The parallels between it and Relational Algebra (in the lattice form) are puzzling. In Algebra of Binary Relations they have two versions of each operator: logical and relative. Composition is relative analog of conjunction, converse is relative analog of negation and so on. In Relational lattice there are two versions of conjunction, two versions of negation and so on. It is natural to extend your question and wonder if types are of any use for Algebra of Binary Relations? Received on Thu Feb 18 2010 - 17:47:15 CET