If This Is a Man to shape the book, giving it a clear sense of direction. In January 1947, the manuscript was rejected by Einaudi. The writers Cesare Pavese and Natalia Ginzburg thought it too early after the war for such an account. Levi managed to find a smaller publisher, De Silva, who printed 2,500 copies of the book, 1,500 of which were sold, mostly in Levi's hometown of Turin. In 1955, Levi signed a contract with Einaudi for a new edition, which was published in 1958. The initial printing of 2000 copies was followed by a second of the same size. An English translation
Hyperbolic geometry The space of relativistic velocities has a three-dimensional hyperbolic geometry, where the distance function is determined from the relative velocities of "nearby" points (velocities). The hyperbolic plane is a plane where every point is a saddle point. There exist various pseudospheres in Euclidean space that have a finite area of constant negative Gaussian curvature. By Hilbert's theorem, it is not possible to isometrically immerse a complete hyperbolic plane (a complete regular surface of constant negative Gaussian curvature) in a three-dimensional Euclidean space. Other useful models of hyperbolic geometry exist in Euclidean space, in which the metric is not preserved. A