\[
\begin{eqnarray}
\underset{\theta}{\operatorname{argmin}} D_{KL}[p^*(Y|X) || p(Y|X;\theta)] &=& \sum_{(x,y) \in D} p^*(y|x) \cdot \log \frac{p^*(y|x)}{p(y|x,\theta)} \\\\\\
&=& \sum_{x \in D} p^*(y|x)[\log p^*(y|x) - \log p(y|x,\theta)] \\\\\\
&=& \sum_{x \in D} p^*(y|x) \log p^*(y|x) - \sum_{x \in D} p^*(y|x) \log p(y|x,\theta) \\\\\\
&=& - \sum_{x \in D} p^*(y|x) \log p(y|x,\theta) \\\\\\
&=& - \sum_{(x,t) \in D} t \cdot \log p(y|x,\theta)
\end{eqnarray}
\]
\[ x^2 \]
\[ x^2 \]
\( y^2 \)
\( y^2 \)
$$ z^2 $$