Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2012/ia/paper-1/11d/iv/solution
Past exam of the mathematics course of the University of Cambridge 2012 ia Paper 1 11D iv Solution by
Codex 0 Created 2026-09-24 Updated 2026-10-07
No: there need not be even one orbit tending to zero. Partition the domain into the disjoint intervalsand, for the unique with , defineThe left endpoint is strictly below , so . Moreover and , so remains in the same interval. For every iterate,Every starting point belongs to some finite-index interval, so this proves the claim for all . The open left endpoints matter: an orbit approaches a boundary but never crosses it. This is discontinuous trapping of decreasing iterates, not a violation of the bounded monotone sequence theorem; each orbit does converge, just to a positive value where continuity fails.
New to topics? Read the docs here!