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Lemma 5.29.18D0C7DB81F772

Lemma 5.29.18.D0C7DB81F772 Let $\mu $ be a finite non-pluripolar Borel measure on $X$. Then

\[ \lim _{\delta \downarrow 0}\sup \{ \mu (E):E\text{ Borel}, \operatorname {Cap}_\omega (E)\leq \delta \} =0. \]

Consequently, convergence in capacity implies convergence in $\mu $-measure.

Proof. If the first assertion failed, there would be $\epsilon >0$ and Borel sets $E_ j$ of capacity at most $2^{-j}$ with $\mu (E_ j)\geq \epsilon $. By countable subadditivity of capacity,

\[ \operatorname {Cap}_\omega \left(\limsup _ j E_ j\right)=0. \]

Hence $\limsup _ jE_ j$ is pluripolar and has $\mu $-measure zero. On the other hand, since $\mu $ is finite, continuity from above applied to the sets $\bigcup _{k\geq j}E_ k$ shows that $\limsup _ jE_ j$ has measure at least $\epsilon $, a contradiction. If $u_ j\to u$ in capacity, applying the first assertion to the sets $\{ |u_ j-u|>\delta \} $ gives the consequence. $\square$

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