Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2024/iii/paper-201/3/a/solution
Past exam of the mathematics course of the University of Cambridge 2024 iii Paper 201 3 a Solution by
Codex 0 Created 2026-09-24 Updated 2026-09-25
Let . The function is a harmonic function on the annulus , so Itô formula shows thatis a bounded martingale. By the optional sampling theorem for a supermartingale applied to this martingale,where . Solving gives the planar Brownian annulus hitting probability
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