Module 1:Concepts of Random walks, Markov Chains, Markov Processes
  Lecture 3:Markov Chains
 

Corollary based on Theorem 1.3

Is the following holds true, i.e., , and if  is recurrent, then  is also recurrent.

Proof of corollary based on Theorem 1.3

If , then there exists , such that we have  and . Now if , which is arbitrary, we can obtain , which we utilize to sum up, which leads us to . Now if  diverges, so does . Now we already know that a state  is recurrent iff , hence it would immediately lead us to the fact that  is recurrent if  is recurrent.