In the framework of discounted Markov decision processes, we consider
the case that the transition probability varies in some given domain a
t each time and its variation is unknown or unobservable. To this end
we introduce a new model, named controlled Markov set-chains, based on
Markov set-chains, and discuss its optimization under some partial or
der.Also, a numerical example is given to explain the theoretical resu
lts and the computation.