I thought that the concept of fuzzy logic was simply that the rules
for solving a problem change based on inputs from the environment.  As an
example, we are in a time of year when some heating is required to make the
house comfortable.  The problem is that there is a great variation from day
to day as to current weather conditions so that if one uses a timer-based or
set-back thermostat to turn up the heat in the morning, one runs the risk of
having heat on when the outside temperature is not cold.  A fuzzy thermostat
controller would have a set-back schedule in it just like the non-fuzzy kind,
but it would also have a thermistor outside to read the current temperature
and would not apply any heat if that were above a certain set point.  The
fuzzy controller  might get input from pin switches in window frames to see
if the residents of the house had opened a window or two during the night
since it would be stupid to turn on any heat if that were the case.

        A fuzzy lawn sprinkler controller would use a timer, but only actually
turn on the water if it was not raining already, an algorithm which appears
to escape the protoplasm-based controllers in the heads of the grounds crew
on our campus.

Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
OSU Center for Computing and Information Services Data Communications Group