James and Ken,
Quite interesting remarks you have made. I agree to Ken's syllogistics and I
love James' consideration on corporeal world practice.
Let's begin at the beginning. What is the requirement level for exceptions of
"MUST NOTs" ?
First, in RFC terms, MAY has the equal value to MAY NOT. In fact, there is no
definition on "MAY NOT" in RFC 2119.
Exceptions to MUST NOTs means there are cases which are not prohibited. The
semantics gives me the implication that the appripriate requirement level is
placed between "SHOULD NOT" and "MAY".
Jiwoong
----- Original Message -----
From: "James P. Salsman" <bovik(_at_)best(_dot_)com>
To: <calvert(_at_)netlab(_dot_)uky(_dot_)edu>
Cc: <porce(_at_)ktf(_dot_)com>
Sent: Saturday, September 22, 2001 5:35 AM
Subject: Re: Exception to "MUST NOT"
Ken,
You have a sharp eye, but the excluded middle of syllogistic logic
has different semantics than the pragmatic logic of restrictions
(such as statutory law and RFC requirements.)
For example, you are not allowed to use a cellphone on a plane, but
will you be prosecuted if you do use one to thwart a hijacking? No.
This is a favorite topic of mine. I hope you do not think I was
trolling, but I was checking to see if any Aristotelians such as
yourself were paying attention.
Cheers,
James
Date: Fri, 21 Sep 2001 16:24:36 -0400 (EDT)
From: Ken Calvert <calvert(_at_)netlab(_dot_)uky(_dot_)edu>
To: "James P. Salsman" <bovik(_at_)best(_dot_)com>
Subject: Re: Exception to "MUST NOT"
(NOT P) does not imply (NOT (C AND P)).
Of course it does.
For any boolean structures P and C,
NOT P
=>
(NOT C) OR (NOT P)
=
NOT (C AND P)
See any text on propositional calculus.
KC