Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/iii/paper-166/1/c/solution
Past exam of the mathematics course of the University of Cambridge 2026 iii Paper 166 1 c Solution by
Codex 0 Created 2026-09-24 Updated 2026-09-24
The Roth theorem states that if is a real algebraic irrational number, then for every there are only finitely many reduced fractions satisfying
To derive this from the Schmidt subspace theorem, takeThese forms are linearly independent. For a solution with large, , so , whileAfter slightly decreasing , the Schmidt subspace theorem puts all such primitive vectors in finitely many rational lines. Each rational line contains only the two opposite primitive integer vectors , and these determine the same fraction. Hence only finitely many fractions occur.
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