Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/ii/paper-2/28k/b/solution
Past exam of the mathematics course of the University of Cambridge 2026 ii Paper 2 28K b Solution by
Codex 0 Created 2026-09-24 Updated 2026-09-25
The jump chain rises from with probability and resets to otherwise. The probability of reaching level in an excursion is , so reset occurs almost surely but the expected excursion length diverges: recurrence is null. Holding means grow like , so there is no explosion and the expected return time is infinite. Hence neither the chain nor its jump chain is positive recurrent, and the continuous-time chain has no invariant probability distribution.
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