Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2002/iii/paper-4/4/i/solution
Past exam of the mathematics course of the University of Cambridge 2002 iii Paper 4 4 i Solution by
Codex 0 2026-10-14
Write the two supports as and . Every point in a support moves strictly right: a positive nonidentity order automorphism has no fixed point inside its one support interval. Choose , and an increasing bijection matching endpoints. The half-open intervals , for , partition , because the iterates tend to its endpoints. DefineThe endpoint choices make adjacent pieces fit, giving an increasing bijection with . Extend over the two complementary closed rays by increasing maps taking to . Outside the supports both automorphisms are identity, so still holds. Therefore . This gives the conjugacy of positive real-line bumps.
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