75. A Markov chain is said to be a tree process if

(i) Image whenever Image,

(ii) for every pair of states i and Image, there is a unique sequence of distinct states Image such that Image In other words, a Markov chain is a tree process if for every pair of distinct states i and j there is a unique way for the process to go from i to j without reentering a state (and this path is the reverse of the unique path from j to i). Argue that an ergodic tree process is time reversible.