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
Differential geometry of surfaces both lie in ). The right hand side is symmetric in and , so the shape operator is self-adjoint on the tangent space. The eigenvalues of are just the principal curvatures and at . In particular the determinant of the shape operator at a point is the Gaussian curvature, but it also contains other information, since the mean curvature is half the trace of the shape operator. The mean curvature is an extrinsic invariant. In intrinsic geometry, a cylinder is developable, meaning that every piece of it is intrinsically indistinguishable from a piece of a plane since its Gauss curvature