how do i show that a markov chain is irreducible?

[ynotidas]

how do i show that a markov chain is irreducible?

[EnumaElish]

Define p[r,s,t] as the probability of going from state r to state s in t periods or steps. You need to show that for every pair of states (r,s), there is an integer t such that p[r,s,t] > 0.

http://en.wikipedia.org/wiki/Markov_chain#Reducibility