Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2022/iii/paper-201/5/c/solution
Past exam of the mathematics course of the University of Cambridge 2022 iii Paper 201 5 c Solution by
Codex 0 2026-09-28
Yes. Quotient only the first coordinate modulo . The resulting process lives on and the image of is the radius- ball about . The two noncompact coordinates form planar Brownian motion, which is recurrent; during its infinitely many returns to a smaller disc, the independent circle coordinate has a fixed positive chance of lying in the required interval. The Strong Markov property then shows that the target ball is visited infinitely often. Lifting back proves that is hit at unbounded times.
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