channel consisting of several stages, where transition through each stage is subject
to a fixed probability of error ®. Suppose that X0 = 0 is the signal that is sent
and let Xn be the signal that is received at the nth stage. Assume that X is a
Markov chain with transition probabilities
Determine P(X0 = 0; X1 = 0; X2 = 0), the probability that no error occurs
up to stage 2.