Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.
Source coverage notes 1 original structured objects have an unresolved mathematical role; their permanent tags identify source occurrences only. Complete original source context · Original author HTML
Proof.
We may assume 0 ≤ h ≤ 1 0\leq h\leq 1 , − M ≤ φ ≤ 0 -M\leq\varphi\leq 0 and
− M ≤ φ j ≤ 0 -M\leq\varphi_{j}\leq 0 for all j j , where M ≥ 1 M\geq 1 .
Given ε > 0 \varepsilon>0 , let G G be an open set such that
Cap ω ( G ) < ε \Capa_{\omega}(G)<\varepsilon and h h is continuous on G c G^{c} , see
Definition 4.4 .
Using the Tietze extension theorem, we extend h | G c h|_{G^{c}}
to a continuous function h ~ \tilde{h} on all of X X such that
0 ≤ h ~ ≤ 1 0\leq\tilde{h}\leq 1 . We then have
∫ h MA ( φ j ) − ∫ h MA ( φ ) \displaystyle\int h\MA(\varphi_{j})-\int h\MA(\varphi)
= ∫ h ~ MA ( φ j ) − ∫ h ~ MA ( φ ) \displaystyle=\int\tilde{h}\MA(\varphi_{j})-\int\tilde{h}\MA(\varphi)
+ ∫ G ( h − h ~ ) MA ( φ j ) − ∫ G ( h − h ~ ) MA ( φ ) . \displaystyle+\int\limits_{G}(h-\tilde{h})\MA(\varphi_{j})-\int\limits_{G}(h-\tilde{h})\MA(\varphi).
It follows from Lemma 4.6 that
| ∫ h MA ( φ j ) − ∫ h MA ( φ ) | ≤ | ∫ h ~ MA ( φ j ) − ∫ h ~ MA ( φ ) | + 2 sup | h − h ~ | M n Cap ω ( G ) . \left|\int h\MA(\varphi_{j})-\int h\MA(\varphi)\right|\leq\left|\int\tilde{h}\MA(\varphi_{j})-\int\tilde{h}\MA(\varphi)\right|+2\sup|h-\tilde{h}|M^{n}\,\Capa_{\omega}(G).
Since h ~ \tilde{h} is continuous,
∫ h ~ MA ( φ j ) → ∫ h ~ MA ( φ ) \int\tilde{h}\MA(\varphi_{j})\to\int\tilde{h}\MA(\varphi) as j → ∞ j\to\infty , thus
lim sup j | ∫ h MA ( φ j ) − ∫ h MA ( φ ) | ≤ 4 ε . \limsup_{j}\left|\int h\MA(\varphi_{j})-\int h\MA(\varphi)\right|\leq 4\varepsilon.
Letting ε \varepsilon tend to zero completes the proof.
∎