Re: Can relvars be dissymetrically decomposed? (vadim and x insight demanded on that subject)

Cimode wrote:
> Tony D wrote:
> > Bob Badour wrote:
> > > Your last statement above overlooks logical independence. A relvar is
> > > not a piece of memory, and it can be a mathematical, logical,
> > > referentially-transparent-placeholder-shorthand-for-an-expression
> > > variable. What, after all, is a view if not a relvar and not a
> > > mathematical, logical,
> > > referentially-transparent-placeholder-shorthand-for-an-expression variable?
> > >
> >
> > Fair point. I forgot that, in the Introduction to Database Systems at
> > least (I don't have TTM here), relvars are noted as coming in two
> > varieties.
> >
> > > Since algebra.
> > >
> >
> > Since I was in the context of a 3GL, I didn't think this objection
> > would come up. Silly of me. I would amend that sentence then to read
> > "Since when was '+' defined over memory references ?"
> > (Casts, BCPL and C-derived lunacy excepted. "*s++" indeed.)
> Yes. I would add a word of caution which is that abstract thinking
> about relations should avoid decutiveness based on implementation. As
> a rule of thumb, I am not sure about some point in RM, I always get
> back to math.
Sorry decutiveness should read *deductiveness*. Received on Tue Jul 18 2006 - 12:47:49 CEST