508

Part of 1989 All Soviet Union Mathematical Olympiad

Problems(1)

ASU 508 All Soviet Union MO 1989 placing arrows on each vertex of a polyhedron

Source:

A polyhedron has an even number of edges. Show that we can place an arrow on each edge so that each vertex has an even number of arrows pointing towards it (on adjacent edges).

polyhedroncombinatorial geometrycombinatorics3D geometryEven