10Strictly speaking, this is not true, because 
will now differ from the value associated with the initial
problem. For purposes of analyzing problems of this kind (announced future changes in parameters) we will
neglect the effects of the path of 
on the equations of motion. Except under extreme circumstances, this
should not change the qualitative results of the analysis, and doing anything else would require a very intricate
analysis. This treatment is admittedly a bit inconsistent, since in the case under consideration it is precisely
the change in 
that motivates the firm to start adjusting its capital stock before the productivity
change comes into effect; effectively, we are taking into account the effect of 
on the level of 
before period 
while neglecting its effects on 
’s dynamics during this interval. C‘est la
vie.