Theorem 11.41.1.7281EDB812F1 The ordinary singularity type of $\varphi $ is described by
\[ \{ u\in \mathrm{PSH}(X,\theta ):u\sim \varphi \} =\{ \varphi +w:w\in \mathrm{PSH}(X,\beta )\cap L^\infty (X)\} , \]
and for each such $w$,
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11.41.2
\begin{equation} \mathrm{MA}^{\mathrm{ext}}_\theta (\varphi +w)=(\beta +\mathrm{dd}^{\mathrm{c}}w)^ n. \end{equation}
For every bounded measurable $F$, the equation (11.33.1) in this ordinary type has a unique constant and a solution unique modulo constants. Its normalization scalar $B_{\theta ,[\varphi ]}$ satisfies
\[ B_{\theta ,[\varphi ]}(F)=B_\beta (F), \]
so its dual functional and supporting sets coincide with $H_\beta $ and $\mathcal A_\beta $.
Proof.
The Poincaré–Lelong formula gives $\theta +\mathrm{dd}^{\mathrm{c}}\varphi =[\Gamma ]+\beta $, so every function on the right is $\theta $-plurisubharmonic and has the type of $\varphi $. Conversely, let $u\in \mathrm{PSH}(X,\theta )$ with $u\sim \varphi $. Then $u$ has the same generic Lelong numbers as $\varphi $ along the components of $\Gamma $, namely the coefficients of $\Gamma $, and lemma 5.38.1 gives
\[ \theta +\mathrm{dd}^{\mathrm{c}}u-[\Gamma ]\geq 0. \]
The locally integrable difference $w=u-\varphi $ therefore has a $\beta $-plurisubharmonic representative. It is bounded off the divisor because $u\sim \varphi $, and the local submean property preserves both bounds across the divisor. Since $u$ and $\varphi +w$ agree almost everywhere, they are equal as quasi-plurisubharmonic functions.
Off the divisor, the currents $\theta +\mathrm{dd}^{\mathrm{c}}(\varphi +w)$ and $\beta +\mathrm{dd}^{\mathrm{c}}w$ agree, and locality identifies their Monge–Ampère products there. The extended measure on the left gives the divisor zero mass, and so does the bounded product on the right, which is finite and charges no analytic set by section 5.28. This proves (11.41.2). In the background $\beta $, the equation with bounded density has a continuous solution and a unique constant by theorem 14.19.2, proposition 14.19.34. The density $\mathrm{e}^ F$ is bounded above and below by positive constants, so corollary 14.24.17 gives uniqueness modulo constants. The correspondence transfers these assertions to the whole ordinary type and identifies the functionals.
$\square$
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