Pome

Lemma 19.5.201493F0A1407E

Lemma 19.5.20.1493F0A1407E Let $T\in \mathcal{Z}_+(X,\alpha )$ be a Kähler current and $\omega $ be a Kähler form on $X$. Then

7D755FB49272 19.5.21
\begin{equation} \Delta _{Y_{\bullet }}(T)\subseteq \Delta _{Y_{\bullet }}(T+\omega ). \end{equation}

Moreover,

2F017272546D 19.5.22
\begin{equation} \Delta _{Y_{\bullet }}(T)=\bigcap _{\epsilon >0}\Delta _{Y_{\bullet }}(T+\epsilon \omega ). \end{equation}

Proof. We first prove (19.5.21). Taking quasi-equisingular approximations, we reduce immediately to the case where $T$ has analytic singularities. By 19.5.11, we may assume that $T$ has log singularities. Take $D$ and $R$ as in (19.5.8). By definition again, it suffices to show that

\[ \Delta _{Y_{\bullet }}(\{ R\} )\subseteq \Delta _{Y_{\bullet }}(\{ R\} +\{ \omega \} ), \]

which is clear by definition.

Next we prove (19.5.22). Thanks to (19.5.21), it remains to prove that both sides have the same volume:

\[ \lim _{\epsilon \to 0+}\operatorname{vol}(T+\epsilon \omega )=\operatorname{vol}T. \]

This is proved in proposition 18.1.27. $\square$

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