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Proposition 18.28.6C9561913A3E8

Proposition 18.28.6.C9561913A3E8 Let $f,g\colon K\rightarrow [-\infty ,\infty ]$ be functions and $\varphi ,\psi \in \mathrm{PSH}(X,\theta )$. Then we have the following:

  1. 33B49F7D21A7

    We have

    \[ P_{\theta ,K}[\varphi ](f)\leq P_{\theta ,K}[\varphi ]_{\mathcal{I}}(f); \]
  2. 6B1193ABBD59

    assume that $f$ is bounded from above, then

    \[ \begin{aligned} \left.P_{\theta ,K}[\varphi ](f)\right|_ K\leq & f\textup{ quasi-everywhere},\\ \left. P_{\theta ,K}[\varphi ]_{\mathcal{I}}(f)\right|_ K\leq & f\textup{ quasi-everywhere}; \end{aligned} \]
  3. 27E6FD2D7332

    suppose that $\varphi \preceq _{\mathcal{I}}\psi $, then

    \[ P_{\theta ,K}[\varphi ]_{\mathcal{I}}(f)\leq P_{\theta ,K}[\psi ]_{\mathcal{I}}(f); \]
  4. B3B86BE1530D

    if $f\leq g$, then

    \[ P_{\theta ,K}[\varphi ](f)\leq P_{\theta ,K}[\varphi ](g),\quad P_{\theta ,K}[\varphi ]_{\mathcal{I}}(f)\leq P_{\theta ,K}[\varphi ]_{\mathcal{I}}(g); \]
  5. 13DB8823929A

    for any $t \in (0,1)$, we have

    \[ \begin{aligned} P_{\theta ,K}\left[t\varphi +(1-t)\psi \right](f)\geq & tP_{\theta ,K}[\varphi ](f)+(1-t)P_{\theta ,K}[\psi ](f),\\ P_{\theta ,K}\left[t\varphi +(1-t)\psi \right]_{\mathcal{I}}(f)\geq & tP_{\theta ,K}[\varphi ]_{\mathcal{I}}(f)+(1-t)P_{\theta ,K}[\psi ]_{\mathcal{I}}(f). \end{aligned} \]

Proof. 1 This follows from $\eta \preceq \varphi \Rightarrow \eta \preceq _{\mathcal I}\varphi $.

2 This follows from proposition 5.14.5 and 5.17.4.

3 This follows by inclusion of the defining candidate sets.

4 This follows by inclusion of the defining candidate sets.

5 If $\eta ,\eta '\in \mathrm{PSH}(X,\theta )$ are such that

\[ \begin{split} & \eta |_ K\leq f\textup{ quasi-everywhere},\quad \eta '|_ K\leq f\textup{ quasi-everywhere},\\ & \eta \preceq \varphi ,\quad \eta '\preceq \psi , \end{split} \]

then for $t\in (0,1)$,

\[ \left.\left(t\eta +(1-t)\eta '\right)\right|_ K\leq f\textup{ quasi-everywhere},\quad t\eta +(1-t)\eta ' \preceq t\varphi +(1-t)\psi . \]

Therefore,

\[ t\eta +(1-t)\eta '\leq P_{\theta ,K}\left[t\varphi +(1-t)\psi \right](f). \]

Since $\eta $ and $\eta '$ are arbitrary, the first inequality follows. The second follows from the same argument. $\square$

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