Re: Principle of Orthogonal Design
From: Tegiri Nenashi <TegiriNenashi_at_gmail.com>
Date: Thu, 7 Feb 2008 09:26:44 -0800 (PST)
Message-ID: <35625fbc-e82b-48f9-b6c5-22e892c8d0f7_at_e10g2000prf.googlegroups.com>
Date: Thu, 7 Feb 2008 09:26:44 -0800 (PST)
Message-ID: <35625fbc-e82b-48f9-b6c5-22e892c8d0f7_at_e10g2000prf.googlegroups.com>
On Feb 7, 3:21 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> A join is not a constraint, is it
There is little controversy what proper constraint definition is. In math we write
x^2 + y^2 = 1
in RA we write an equation with relational operators. Now, equality constraints are not general enough, so you need inequality as well, and there is indeed such a thing. Now, the thesis:
Every constraint can be expressed as a system of relational inequalities.
To put this into the scope of the cited question, no join is an operation, and not a constraint. Received on Thu Feb 07 2008 - 18:26:44 CET