Mu
(Greek letter).
1. /micro/ prefix denoting division by 10^6, e.g. mu m
(micrometre, a millionth part of a metre). Sometimes written
as a 'u', the ASCII character nearest in appearance.
2. /myoo/ In the theory of functions, mu x . E
denotes the least value of x for which E ◦ x, i.e. the {least
fixed point} of the function \ x . E. The {recursive}
function mu f . H f satisfies (and is defined by) the equation
mu f . H f ◦ H (mu f . H f)
An alternative notation for the same function is
fix H ◦ H (fix H)
See {fixed point combinator}.
3. /moo/ The correct answer to the classic trick question
"Have you stopped beating your wife yet?". Assuming that you
have no wife or you have never beaten your wife, the answer
"yes" is wrong because it implies that you used to beat your
wife and then stopped, but "no" is worse because it suggests
that you have one and are still beating her. According to
various Discordians and Douglas Hofstadter the correct answer
is usually "mu", a Japanese word alleged to mean "Your
question cannot be answered because it depends on incorrect
assumptions".
Hackers tend to be sensitive to logical inadequacies in
language, and many have adopted this suggestion with
enthusiasm. The word "mu" is actually from Chinese, meaning
"nothing"; it is used in mainstream Japanese in that sense,
but native speakers do not recognise the Discordian
question-denying use. It almost certainly derives from
overgeneralisation of the answer in the following well-known
Rinzei Zen teaching riddle:
A monk asked Joshu, "Does a dog have the Buddha nature?"
Joshu retorted, "Mu!"
See also {has the X nature}, {AI Koan}, and Douglas
Hofstadter's book, "G�del, Escher, Bach: An Eternal Golden
Braid".
4. {multiple value}.
[{Jargon File}]
(1995-10-30)