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From: vadimtro@gmail.com
Newsgroups: comp.databases.theory
Subject: Re: Onto a potential relational manipulation language
Date: Fri, 12 Dec 2008 13:37:17 -0800 (PST)
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On Dec 12, 1:29=A0pm, vadim...@gmail.com wrote:

> Next,
>
> (x v y) v z =3D z
>
> that is z contains a subset of attributes common to x and y. With
> these assumptions the projection

Typo, again! The correct condition is

((x v y) v z) ^ R00 =3D z

The implication

z ^ R00 =3D z &
((x v y) v z) ^ R00 =3D z
->  (x + y) v z =3D (x v y) v z.

is still a theorem in RL.