Problem

Source: BMO Shortlist 2022, C3

Tags: combinatorics, AZE EGMO TST, AZE BMO TST



Find the largest positive integer $k{}$ for which there exists a convex polyhedron $\mathcal{P}$ with 2022 edges, which satisfies the following properties: The degrees of the vertices of $\mathcal{P}$ don’t differ by more than one, and It is possible to colour the edges of $\mathcal{P}$ with $k{}$ colours such that for every colour $c{}$, and every pair of vertices $(v_1, v_2)$ of $\mathcal{P}$, there is a monochromatic path between $v_1$ and $v_2$ in the colour $c{}$. Viktor Simjanoski, Macedonia