>>>>> "SN" == Sean Neakums <sneakums@zork.net> writes:

    SN> commence Kai Gro?johann quotation:
    >> Dan Christensen <jdc@uwo.ca> writes:
    >> 
    >> > Hmm, I can't reproduce this anymore.
    >> 
    >> I've also not seen lost expirable marks in the last 1 or 2
    >> days.  Fascinating.  A Heisenbug is when the behavior is
    >> unpredictable.  So is a Schroederbug the case where the bug
    >> goes away if you look for it?

    SN> I always thought the latter definition was that of a
    SN> Heisenbug.  I had one of those once, but I've forgotten the
    SN> details.  I recall it involved some C code and gdb.

I'll second that. So does the Jargon File[0]:

# heisenbug /hi:'zen-buhg/ n.

# [from Heisenberg's Uncertainty Principle in quantum physics] A bug
# that disappears or alters its behavior when one attempts to probe or
# isolate it.

Conversely, a 'schroedinbug' is "A design or implementation bug in a
program that doesn't manifest until someone reading source or using
the program in an unusual way notices that it never should have
worked, at which point the program promptly stops working for
everybody until fixed."

An "unpredictable" (quoth Kai) bug is a mandelbug:

# [from the Mandelbrot set] A bug whose underlying causes are so complex
# and obscure as to make its behavior appear chaotic or even
# non-deterministic. This term implies that the speaker thinks it is a
# Bohr bug, rather than a heisenbug. See also schroedinbug.

--Joe

[0] http://www.tuxedo.org/~esr/jargon/html/The-Jargon-Lexicon-framed.html[1]

[1] Is there a gnus add-on for auto-numbering footnotes like these?
    Can one, for instance, use a LaTeX-like syntactic construct to
    indicate footnote content, and run a function to process the
    footnotes before sending the message?