Suppose a Markov process with the set of states A is reversible and has steady-state probabilities pi, i ∈ A. Let B be a subset of A and assume that the process is changed by setting qij = 0 for all i ∈ B, j ∈/ B. Assuming that the new process (starting in B and remaining in B) is irreducible, show that the new process is reversible and find its steady-state probabilities.