Topics: Markov Chain - Ergodic Set
(definition)
An ergodic Markov chain, also known as irreducible, is Markov chain that only has a single class. Since there is only one class, it follows that this class is an ergodic set.
There are two types of ergodic Markov chains: cyclical and regular chains. The set of cyclical chains is the complement of the set of regular chains.