Let {Xn : n ≥ 0} be a Markov chain with state space {0, 1, 2, 3} and transition matrix P =
(1/4 0 1/2 1/4)
(0 1/5 0 4/5)
(0 1 0 0)
(1/3 1/3 0 1/3)
(a) Draw a state space diagram for the process {Xn : n ≥ 0}.
(b) Compute P(X17 = 1, X15 = 0, X14 = 3, X12 = 2 | X10 = 3), justifying each step carefully.
A new process {Zn : n ≥ 0} is defined by Zn = 0 if Xn = 0 or 1, and Zn = Xn if Xn = 2 or 3.
(c) Write down the state space of the process {Zn : n ≥ 0}.
(d) Find P(Zn+1 = 2 | Zn = 0, Zn-1 = 2).
(e) Find P(Zn+1 = 2 | Zn = 0, Zn-1 = 3).
(f) Is Z0, Z1, Z2, ... a Markov chain? Why?
HINT: to find these probabilities, think what the equivalent value for Xn would be. For example, if Zn = 2 then we must have that Xn = 2. By doing this, you can use the probabilities in the transition matrix for {Xn : n ≥ 0}.