Re: x*x-1=0

In article <949sjq$k1s$3_at_news.tue.nl>,   hidders_at_win.tue.nl (Jan Hidders) wrote:
> wrote:
> > What the closest analog of
> > x^2-1=0
> > in relational algebra would be? Does
> > A MULTIPLY B MULTIPLY C
> > have any resemblance to power 2?
>
> Not really, it is more just like multiplication. A better kind of
> candidate would be the powerset operation that you sometimes find in
> some nested relational algebras.
>
> --
> Jan Hidders
>
Jan,

Thank you for the reference. Before doing my howework, though, a newbie question: Overall, are nested algebras a kind of generalization that pays of? Is it more elegant? Does it have less number of atomic operators? I, personally, have difficulties understanding simple relational model, could I hope to get some new insights from nested one?

BTW, the expression above should really read as x MULTIPLY x
of course. And I see that since number 2 is not a table literal, it is difficult to extrapolate it to x^2.
But I don't necessarily have to. My question is about our abilities solving equations in Relational Algebra, whatever operation definitions are. (Although, Distributive, Commutative, and Associative laws would help:-). For example,

x MULTIPLY A UNION B = DUM

where A and B some table constants and x is rel var.

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http://www.deja.com/ Received on Fri Jan 19 2001 - 19:34:31 CET