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Re: completeness of the relational lattice

From: Vadim Tropashko <vadimtro_invalid_at_yahoo.com>
Date: Fri, 22 Jun 2007 17:39:02 -0700
Message-ID: <1182559142.522877.151260@z28g2000prd.googlegroups.com>


On Jun 22, 5:27 pm, Marshall <marshall.spi..._at_gmail.com> wrote:
> > Sure x,y,z have to belong to the same domain, while "a" and "b" may be
> > from a different domain. This is again an informal definition that is
> > supposed to drive the intuition.
> Hmm. I don't get that. Also, is there any significance to the fact
> that x=y and a=b are enclosed in different kinds of quotes?

No, the quote around a was suposed to distinguis it from article:-) I should have put quoyes around x,y,z, but being lazy.

What I meant is that Equality relation looks like this:

x y z a b



1 1 1 i i
1 1 1 j j
2 2 2 i i
2 2 2 j j
3 3 3 i i
3 3 3 j j

where x,y,z are from domain integers, and a and b from the domain of "i" and "j" letters.

> Let me just say that I think that domains are pure distraction,
> best ignored.

No wonder you don't accept element 11. Because 11 \/ R produces a cartesian product of domains. If R /\ 00 is atomic, then 11 \/ R is an individual domain. Received on Fri Jun 22 2007 - 19:39:02 CDT

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