“It was only after many brilliant mathematicians had struggled with the idea that the dark and obscure landscape of divergent series was illuminated, and mathematicians finally decided what a divergent series ‘really is’ and how they could safely be handled. Euler's relation for polyhedra A similar confusion arose over another of Euler's interests: polyhedra. He noticed what Descartes had also seen earlier that for the simplest polyhedra, the number of vertices plus the number of faces exceeded... the number of edges by 2: V + F = E + 2. Thus, in Figure 10.1 a cube has 8 vertices, 6 faces and 12 edges, and 6 + 8 = 14 + 2. The octahedron on the right has 6 vertices, 8 faces and also 12 edges, while the irregular polyhedron below which is a square pyramid face-to-face with a cube, has 9 vertices, 9 faces and 16 edges, and 9 + 9 = 16 + 2. Figure 10.1 Diagram of cube, octahedron and pyramid ON cube Naturally such simple observations cry out for an explanation, but all the early proofs were defective.MoreLessRead More Read Less
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