Elaboration of a step in the proof of Fatou's Lemma (Royden $4^{th}$ edition pg.82).

83 Views Asked by At

The lemma and a part of its proof are given below:

enter image description here enter image description here

My question is:

Why $h_{n}(x) \rightarrow h(x)$? could anyone explain this for me, please?

1

There are 1 best solutions below

4
On BEST ANSWER

Because $h \le f$ then for any $x$ then $h(x)=f(x)$ or $h(x)<f(x)$. The convergence in the first case is clear from the definition of $h_n$, now suppose that $h(x)<f(x)$, then from the definition of $h_n$ we have that $h_n(x)=h(x)$ for all $n\ge N$ for some large enough $N\in\Bbb N$.