Pome

Proposition 11.39.1675DA440E964

Proposition 11.39.1.675DA440E964 Let $\varphi ,\psi $ satisfy (16.28.67). If $\varphi \preceq \psi $, then $B_\varphi \leq B_\psi $ and $H_\varphi \leq H_\psi $. Moreover, if $0<\varepsilon <1$ and $P_{\varepsilon \theta }(\varphi )\not\equiv -\infty $, then

\[ B_0(G)+n\log (1-\varepsilon ) \leq B_\varphi (G)\leq B_0(G) \qquad (G\in C(X)), \]

and

\[ H_0(\nu )+n\log (1-\varepsilon ) \leq H_\varphi (\nu )\leq H_0(\nu ) \qquad (\nu \in \mathcal P(X)). \]

The dual inequalities include infinite values.

Proof. Fix $G$, and let $u_\varphi ,u_\psi $ solve the equations in the ordinary types of $\varphi $ and $\psi $, with constants $c_\varphi ,c_\psi $. Then $u_\varphi \preceq u_\psi $. If $c_\varphi >c_\psi $, the singular strict domination principle applied to $u_\psi $ and $u_\varphi +t$ would give $u_\psi \geq u_\varphi +t$ for every real $t$, which is impossible at a point where both are finite. This proves the monotonicity of $B$, and taking the defining supremum gives the monotonicity of $H$. Since $\varphi \preceq 0$ and the zero potential is itself a model reference, this also proves both upper bounds.

For the lower bound, let $v$ be a bounded solution for $G$ with the zero reference, with constant $c_0$, and put

\[ h=P_{\varepsilon \theta }(\varphi )+(1-\varepsilon )v. \]

The two summands are $\varepsilon \theta $- and $(1-\varepsilon )\theta $-plurisubharmonic, respectively, so positivity and homogeneity give

\[ \mathrm{MA}^{\mathrm{ext}}_\theta (h) \geq (1-\varepsilon )^ n\mathrm{MA}_\theta (v) =(1-\varepsilon )^ nc_0\mathrm{e}^ G\, \mathrm{d}V. \]

As in the proof of lemma 15.12.2, this inequality is justified first on finite truncation levels and then off the pole set of $P_{\varepsilon \theta }(\varphi )$, which has zero smooth volume. Also $h\preceq u_\varphi $. If $c_\varphi <(1-\varepsilon )^ nc_0$, strict domination would force $u_\varphi \geq h+t$ for every $t$. Thus $c_\varphi \geq (1-\varepsilon )^ nc_0$. Taking logarithms proves the scalar bound, and taking the defining suprema proves the dual bound. $\square$

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