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Re: De Morgan's theorum
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From:
Paul Johnson
Date:
February 20, 2002 13:03
Subject:
Re: De Morgan's theorum
Message ID:
20020220230216.F16426@pjcj.net
On Wed, Feb 20, 2002 at 07:04:44PM +0000, Nick Ing-Simmons wrote:
> Brian Lee Ray <blray@ualr.edu> writes:
> >From: "Nicholas Clark" <nick@unfortu.net>
> >Sent: Tuesday, February 19, 2002 3:15 PM
> >Subject: De Morgan's theorum
> >> I have remembered the name correctly, haven't I?
> >Yes. If we were really serious about optimizing logical expressions,
> >we would probably want to use Karnaugh maps.
>
> Karnaugh maps are for Humans with visual ways of understanding.
> There is an easy-to-code Algorithm (Quine McLusky?) which does
> the job for computers - it it can handle what would be (projection of)
> an n-Dimensional hyper cube of a Karnaugh map.
Unfortunately this problem is NP-complete and Quine-McClusky is an exact
algorithm. A heuristic algorithm like espresso might be better, but
> >However, I just don't
> >think most programs spend enough time doing logical comparison to
> >really matter. Besides which, such techniques work best on complex
> >expressions, which are rare indeed.
I suspect this is true.
--
Paul Johnson - paul@pjcj.net
http://www.pjcj.net
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