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I am learning current theory presently. In Chap 3.3-Definition of Monge-Ampère Operators, J.-P. Demailly, Complex analytic and differential geometry, I am a little confused as follows.

Let $X$ be a n-dimensional complex manifold. Let $u$ be a locally bounded plurisubharmonic function on $X$ and let $T$ be a closed positive current of bidimension $(p, p),$ i.e. of bidegree $(n-p, n-p) .$ Demailly defined the wedge $$ d d^{c} u \wedge T=d d^{c}(u T), $$ where $d d^{c}(\quad)$ is taken in the sense of distribution (or current) theory. Then he proved the following proposition.

Propostion The wedge product $d d^{c} u \wedge T$ is again a closed positive current.

Proof. The result is local. In an open set $\Omega \subset \mathbb{C}^{n},$ we can use convolution with a family of regularizing kernels to find a decreasing sequence of smooth plurisubharmonic functions $u_{k}=u \star \rho_{1 / k}$ converging pointwise to $u .$ Then $u \leqslant u_{k} \leqslant u_{1}$ and Lebesgue's dominated convergence theorem shows that $u_{k} T$ converges weakly to $u T ;$ thus $d d^{c}\left(u_{k} T\right)$.........

My question: In the above argument, Lebesgue's dominated convergence theorem is used. As we all know, Lebesgue's dominated convergence theorem reveals something about the integral. However, $T$ may be not the current induce by an $L_{\operatorname{loc}}^{1}$ function. So How can we apply Lebesgue's dominated convergence theorem to $u_{k} T$? Anyone know something similar with Lebesgue's dominated convergence theorem in the general current theory?

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    $\begingroup$ A positive current is of order 0 $\endgroup$ Commented Sep 5, 2020 at 13:41
  • $\begingroup$ @RichardL Why can we apply the Lebesgue's dominated convergence theorem to the current of order 0? Does the current of order 0 act on test forms by integration? Where can I find such material? Thank you. $\endgroup$
    – jack lion
    Commented Sep 6, 2020 at 6:14
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    $\begingroup$ Indeed, a current or distribution of order 0 acts by integration against a (signed) measure (and when the current is positive, the measure is positive). These questions don't really seem on topic for this site ("mathematical questions related to current research in mathematics"), but should be covered if you study distribution theory and measure theory properly (positive distributions, distributions of order 0, appropriate versions of the Riesz representation theorem). $\endgroup$ Commented Sep 7, 2020 at 7:34

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