\(f_{ii}<1\). In otherwords, the probability of reaching state \(i\) eventually, starting from state \(i\) is
not certain. i.e. there will be a chance that starting from \(i\,\), chain will never again get
back to state \(i\).
\({\displaystyle \sum \limits _{n=0}^{\infty }} p_{ii}^{\left ( n\right ) }<\infty \), in otherwords, since sum converges, this means the probability to return back to \(i\)
starting from \(i\) will NOT always exist (i.e. sum terms reach all zeros after some limiting
value \(n\))