A note on the structure of plurifinely open sets and the equality of some complex Monge-Amp\`ere measures

Abstract

In a recent preprint published on arXiv (see arXiv:2308.02993v2, referred here as \cite{NXH}), N.X. Hong stated that every plurifinely open set $U\subset \mathbb{C}^n$, $n\geq 1$, is of the form $U=\bigcup \{\varphi_j>-1\}$, where each $\phi_j$ is a negative plurisubharmonic function defined on an open ball $B_j\subset \mathbb{C}^n$ and used this result to prove an equality result on complex Monge-Amp\`ere measures. Unfortunately, this result is wrong as we will see below.