 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2025/ii/paper-4/17f/b/i/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

Choose any vertex

v

K_{2 t}

. Its

2 t - 1

incident edges have two colours, so at least

⌈ \frac{2 t - 1}{2} ⌉ = t

have the same colour. Those edges, together with

v

, form a monochromatic

K_{1, t}

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