Dynamic programming and Bellman Equation

 

We consider the following maximization problem

         

where

   for t=0,2,4,6,. . .

and

   for t=1,3,5,7,. . .

where we now switch utility function from leisure with weight.

 

The corresponding Bellman equations are

and

We guess

 

 and

 

Then we have

and

FOCfs are

 and 

and

 and 

for each state.

 for state 1   (*)

 for state 2   (*)

 

For state 1

   at optimum

For state 2

   at optimum 

from the results in 0508 with (*) and (**) above. For l1* and l2*

 for state 1   (*)

 for state 2   (*)

 

The Bellman equations are now going to be

and

They are

and

 

Arranging terms and comparing the coefficients,

 

 and 

so

that is the same as yesterday.

 

The rest is

and

 

Thus

 

We have solved out and the guess is right.

 

The policy functions are

 for state 1 

 for state 2

Here, from

   for state 1

and

   for state 2

where they are constant.

 

Once we solve l1* and l2* together with other parameters, we can get kf for each state.