Re: A different definition of MINUS, Part 3

From: paul c <>
Date: Sun, 21 Dec 2008 08:39:07 -0800
Message-ID: <Lhu3l.50534$mY6.5616_at_newsfe10.iad>

Walter Mitty wrote:
> "paul c" <> wrote in message
> news:5h83l.48993$mY6.41775_at_newsfe10.iad...

>> A-algebra operators, just to remind, there are fundamentally only three of 
>> those, some of the ones typically used are merely derivations of those 
>> three, you can say there are four if TCLOSE is included), that allows a 
>> language implementation that is not only effective for some purpose, but 
>> closed for the desired expressions of that language.

> Are the three fundamental ones <AND> <OR> & <NOT>?
> ...

I believe it is arbitrary as to whether you want (<AND>, <NOT>) = <NAND> to be fundamental or (<OR>, <NOT>) = <NOR> to be fundamental. This is akin to the corresponding Boolean operators. Projection and <REMOVE> are always fundamental. TCLOSE could be fundamental too, if one desires it.

> If so, is it possible to define a <NAND> such that <AND> <OR> & <NOT> can
> be derived from <NAND>?
> as in <NOT> A = A <NAND> A
> etc.?

I believe so. Received on Sun Dec 21 2008 - 17:39:07 CET

Original text of this message