Re: Examples of SQL anomalies?

From: Marshall <marshall.spight_at_gmail.com>
Date: Mon, 30 Jun 2008 15:51:23 -0700 (PDT)
Message-ID: <c86e77e6-4632-4697-8d51-0d594f967b2d@h1g2000prh.googlegroups.com>


On Jun 30, 2:23 pm, -CELKO- <jcelko..._at_earthlink.net> wrote:
>
> When the gas gauge of my car says zero, that is an actual measurement
> using a ratio scale with a natural origin point. When I talk about
> putting gas in my Lamborghini, it makes just as much sense to talk
> about putting -10 liters into the gas tank. When something does not
> exist, then you can say anything.
>
> Basic logic:
> 1) A false premise can imply a true or a false conclusion.
> 2) A true premise can only imply a true conclusion.

You're mixing up nonexistence with emptiness. The empty set exists. We can count how many members it has. That count is zero. We can add up all the numbers in it and get a total; that total is zero. We can also multiply all the numbers in it together and get a product; that product is 1. We can AND together all the booleans in it and get a boolean value; that value is TRUE. Having things work this way is simpler than if we don't.

However we cannot count the members of the set of all sets that don't contain themselves as members, because there is no such set.

Marshall Received on Mon Jun 30 2008 - 17:51:23 CDT

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