Let $X$ be a Polish space and $C(X)$ denote the space of all bounded and continuous functions on $X$. We consider a Markov chain $(\xi_n)_{n\geq 0}$ with transition probability $P:X\times \mathcal{B}_X \rightarrow \left[0,1\right]$ and assume that the related Markov semigroup $(P^n)_{n\geq1}$ satisfies the Chapman–Kolmogorov equation: $P^{n+1}(x,A)=\int\limits_{X}P^n(y,A)\,P(x,dy), \mbox { for } x\in X,\, A\in \mathcal{B}_X.$ Routinely, we define a dual operator $U^n$ related to $P^n$ as follows: $U^n f(x)=\int\limits_{X} f(y)P^n(x,dy), \mbox{ for any } f\in C(X)$ and Markov operator: $P^n \mu (A)=\int\limits_{X} P^n(x,A)\, \mu(dx), \mbox{ for any } A\in \mathcal{B}_X$ We also assume that $P$ has the Feller property, that means, $Uf \in C(X)$, for any $f\in C(X)$.
Recently, I've proved the following theorem:
If the chain $(\xi_n)_{n\geq 0}$ has the Feller property and the following conditions are satisfied:
(i) for all $f\in C(X)$ with bounded support the family $\{U^n f: n \in \mathbb{N}\}$ is equicontinuous in each point of $X$,
(ii) the family of measures $\{P^n(x, \cdot): n\in\mathbb{N}\}$ is tight, for any $x\in X$,
(iii) there is a point $z\in X$ such that $\bigwedge\limits_{\delta>0}\, \bigvee\limits_{N\in\mathbb{N}}\,\bigwedge\limits_{x\in X}\,P^N(x,B(z,\delta))>0$,
then, there is an unique probabilistic invariant measure for $(\xi_n)_{n\geq 0}$ and $(P^n(x,\cdot))_{n\geq1}$ converges to $\pi$ weakly and uniformly in $x$ from compact subsets of X.
I have problems with two things:
Does the sequence $(P^n \mu)_{n\geq 1}$ also converge weakly to $\pi$, for any probabilistic measure $\mu$ on $X$? (I know, that the set of point measures is dense in space of all probabilistic measures with weak topology, but I cant use it without the nonexpansivity $P$ in the total variation norm).
Could anyone give an example of Markov - Feller chain, which satisfied conditions (i) - (iii)?
I will be very grateful especially for answer to my second question.