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Point estimate of $ \beta _g$

We approximate $ \widehat{\beta}_g$ using the point estimate $ \widehat{\sigma_g^2}$ and $ \vec{\tau_K=1}$:

$\displaystyle \widehat{\beta}_g$ $\displaystyle =$ $\displaystyle \arg \max_{\beta_g}
p(\beta_g\vert Y,\sigma_g^2=\widehat{\sigma_g^2},\vec{\tau_K=1})$ (46)

where $ p(\beta_g\vert Y,\sigma_g^2=\widehat{\sigma_g^2},\vec{\tau_K=1})$ is equation 15 with $ \sigma_g^2=\widehat{\sigma_g^2}$ and $ \vec{\tau_K=1}$. The solution to this is:
$\displaystyle \widehat{\beta}_g$ $\displaystyle =$ $\displaystyle (X_{G}^T U^{-1}
X_{G})^{-1}X_{G}^TU^{-1}\vec{\mu_{\beta_K}}$ (47)

with $ U$ as in equation 15, but with $ S_k =
(\sigma_{\beta_k}^2\Sigma_{\beta_k})+\widehat{\sigma_g^2}I$.