Pome

Lemma 16.28.68F644817639FD

Lemma 16.28.68.F644817639FD Let $\varphi $ be a model reference. If $u\in \mathcal E_\varphi $ and $u\leq \varphi $, then

\[ w=P_\theta (u-\varphi )\in \mathcal E_0, \qquad w\leq 0, \qquad w+\varphi \leq u. \]

Proof. Since $\varphi \leq 0$, the potential $u$ lies below the obstacle $u-\varphi $ away from the pole set of $\varphi $, so it is a competitor. Hence the envelope $w$ is not identically $-\infty $. It is at most zero, since $u-\varphi \leq 0$, and it satisfies $w+\varphi \leq u$ off the poles, hence everywhere by lemma 5.24.3. For $b\geq 1$, let $h_ b=Q_ b(u,\varphi )$. Then, off the poles,

\[ h_ b\leq bu-(b-1)\varphi \leq b(u-\varphi ). \]

Since $\theta \geq 0$, the function $b^{-1}h_ b$ is $\theta $-plurisubharmonic, and so it is a competitor for $w$. Hence $h_ b\leq bw$, so $\mathcal A_ b(w,0)$ is nonempty for every $b$. Since also $w\leq 0$, this means exactly that $w\in \mathcal E_0$. $\square$

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