Solution
= Solution
The posterior is Pareto with shape $\alpha+n$ and lower endpoint $m=\max\{\ell,X_{(n)}\}$. Minimizing $E[(\delta-\theta)^2/\theta^2\mid X]$ gives $\delta=E(\theta^{-1}\mid X)/E(\theta^{-2}\mid X)$, hence
$$
\boxed{\hat\theta_{\alpha,\ell}=m\frac{\alpha+n+2}{\alpha+n+1}.}
$$