Find all n such that any convex n-gon in the plane can be divided into finite number of triangles satisfying the following conditions.
(i) No vertex is added to the sides of the n-gon. However, any number of vertices can be added to the interior of the n-gon. (ii) All triangles have exactly three bounding edges and the edges intersect only on vertices. (iii) Each vertex has an even number of edges connected to it.
Solution
This is essentially Exercise 6.4.10 from Invitation to Discrete Mathematics, 2nd edition, Oxford University Press, by Jiří Matoušek and Jaroslav Nešetřil.
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