Re: A different definition of MINUS, Part 3
Date: Sun, 21 Dec 2008 08:39:07 -0800
Walter Mitty wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
>> 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
I believe so. Received on Sun Dec 21 2008 - 17:39:07 CET