Solution (source code)

= Solution

An irreducible nonexplosive <continuous-time Markov chain> has an equilibrium probability distribution exactly when it is positive recurrent. The distribution is unique, and gives the long-run fraction of elapsed time in each state. A null recurrent chain has no equilibrium probability distribution. The finite one-state absorbing case is trivially stationary; the return-cycle descriptions concern nontrivial irreducible classes.