正規化された分配凾数(2)
$$
\begin{eqnarray}
Z_n(\beta)
&=&\int_\Theta
\pi(\theta)\prod_{i=1}^n q(X_i;\theta)^\beta
\mathrm{d}\theta\\
&=&\int_\Theta
\pi(\theta)\prod_{i=1}^n \left\{q(X_i;\theta_0)\exp\left(-f(X_i,\theta_0,\theta)\right)\right\}^\beta
\mathrm{d}\theta
\;\cdots\;\href{https://shikitenkai.blogspot.com/2020/05/blog-post_1.html}{q(X_i;\theta)^\beta=\left\{q(X_i;\theta_0)\exp\left(-f(X_i,\theta_0,\theta)\right)\right\}^\beta}\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) \int_\Theta
\pi(\theta) \prod_{i=1}^n \exp\left(-f(X_i,\theta_0,\theta)\right)^\beta
\mathrm{d}\theta\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) \int_\Theta
\pi(\theta) \prod_{i=1}^n \exp\left(-\beta f(X_i,\theta_0,\theta)\right)
\mathrm{d}\theta\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) \int_\Theta
\pi(\theta) \exp\left(-\beta \sum_{i=1}^n f(X_i,\theta_0,\theta)\right)
\mathrm{d}\theta
\;\cdots\;\prod_{i=1}^n \exp\left(A_i\right) = \exp \left(\sum_{i=1}^n A_i\right)\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) \int_\Theta
\pi(\theta) \exp\left(-\beta\;nK_n\right)
\mathrm{d}\theta
\;\cdots\;\sum_{i=1}^n f(X_i,\theta_0,\theta)=nK_n(\theta)\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) \int_\Theta
\pi(\theta) \exp\left(-n\beta K_n\right)
\mathrm{d}\theta\\
&=&\left(\prod_{i=1}^n q(X_i;\theta_0)^\beta\right) Z_n^{(0)}(\beta)
\;\cdots\;Z_n^{(0)}(\beta)=\int_\Theta \pi(\theta)\exp(-n\beta K_n(\theta))\mathrm{d}\theta:正規化された分配凾数\\
&=& Z_n^{(0)}(\beta)\prod_{i=1}^n q(X_i;\theta_0)^\beta\\
\end{eqnarray}
$$
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