Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.os.linux.advocacy
Subject: Re: Why Python When There Is Perl?
Date: Sat, 23 Mar 2024 22:06:37 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 26
Message-ID: <utnjpc$3sqhf$3@dont-email.me>
References: <17be420c4f90bfc7$63225$1585792$802601b3@news.usenetexpress.com>
	<utd86u$1ipcj$1@solani.org>
	<17be75acfaf8f0f4$2017$3384359$802601b3@news.usenetexpress.com>
	<utfol0$1k8j7$1@solani.org>
	<17bebbae334656b9$74345$2906873$802601b3@news.usenetexpress.com>
	<utiopt$2i4i5$1@dont-email.me>
	<17bf321f9c15028e$2$2218499$802601b3@news.usenetexpress.com>
	<utlbto$38pmm$1@dont-email.me> <utltt2$1n3m4$1@solani.org>
	<utniif$1o32m$2@solani.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Sat, 23 Mar 2024 22:06:37 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="8288a6795704a6fce0c976674ad0a261";
	logging-data="4090415"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18cOllj+mrgu2cdOplSM1TW"
User-Agent: Pan/0.155 (Kherson; fc5a80b8)
Cancel-Lock: sha1:N2QVWgF/O8Pmn3uXPfLoQnxZzDc=
Bytes: 2292

On Sat, 23 Mar 2024 16:45:51 -0500, Physfitfreak wrote:

> But, what is wrong with taking the absence of a condition as a condition
> of its own, and not as the negated form of that condition?

Aka “the law of the excluded middle”. Remember, we are working in an 
algebra where variables only have two possible values. If you want to add 
a third value, you end up with a different algebra.

For an example of the difference this makes, in conventional number 
algebra, you may already know the distributivity rule:

    A(B + C) = AB + AC

In Boolean algebra, you also have this distributivity rule:

    A + BC = (A + B)(A + C)

There is a duality between true and false, 1 and 0, which allows you to 
flip any theorem around by interchanging the two, and making some other 
simple transformations. For example, De Morgan’s theorems:

    ¬A ∨ ¬B = ¬(A ∧ B)
    ¬A ∧ ¬B = ¬(A ∨ B)

Notice the symmetry between them.