where is the rate at which temporary quitters quit smoking permanently. We assume that the class of potential
smokers is increased by the recruitment of individuals at a rate In model 2, the total population is constant
and () () (),() are respectively the proportions of potential smokers, smokers, temporarily quitters and
permanent quitters where () + () + () +() = 1 . Instead of analyzing model 2 we will only consider the
following subsystem: