We consider the following maximization problem
subject to ![]()
We introduce technology shock that is a random process. That is
![]()
where
![]()
for ![]()
We consider the following Bellman equation
We start from E[V0|theta]=0 and k’=0.
![]()
Since
and k’=0
![]()
![]()
That is
![]()
Since ![]()
![]()
FOC w.r.t. k’ is
![]()
![]()
So
![]()
Plugging it into Bellman equation at optimum when j=1
![]()
Arranging the first term on the right hand side, we get
![]()
In term of k and theta, we can express it as
![]()
![]()
We can express it as
![]()
We can repeat this.
![]()
That is
![]()
FOC w.r.t. k’ is
![]()
![]()
So
![]()
At least we can calculate k’ in the same way and we get
when j=n.
That is going to become

Thus
![]()
That’s what we got in 0511 by the method of guess and verify. That is not difficult.
However, the generalization of value function is a little bit complicated.