Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2002/iii/paper-40/4/a/iv/solution

We prove convergence of the actual sequential updates above, not just concentration of ideal equilibrium distributions. Write and . Given , the centered normal draw satisfies
The conditional inverse-gamma distribution moments therefore give
For , the coefficient multiplying is at most , so stays bounded by a geometric-recursion argument. The coefficient multiplying is at most , and the other terms are bounded using the first-moment bound, so also stays bounded. These bounds start from the finite deterministic .
Since , the boundedness makes every term containing or vanish. Hence and . Consequently
Thus
This establishes mean-square convergence for the specified Gaussian annealer. It does not assert that every implementation or cooling rule for every objective has the same guarantee, nor that mean-square convergence alone is almost-sure convergence.

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