ICM'98

Weierstrass's school of analysis and its influence on Italian Mathematics
By Umberto Bottazzini

Berlin emerged as the leading centre of mathematical analysis in the early 1860s when Weierstrass, who had joined Kronecker and Kummer in 1856, began to teach the theory of analytic functions at the university and founded the mathematical seminar together with Kummer. In autumn of 1864 the Italian mathematician Casorati visited Berlin to discuss with Weierstrass, Kronecker, Kummer and their pupils the most recent progress in mathematics. The notes taken by Casorati of the talks with the Berlin mathematicians provide a vivid picture of the questions which were then at the forefront of mathematical research. In particular, they discussed such topics as continuity, differentiability, analytic continuation, natural boundaries, and Riemann's use of the Dirichlet principle. The latter became the main subject of the correspondence between Casorati and Schwarz, the student of Weierstrass who mostly contributed to the diffusion of his teacher's methods in Italy. Indeed, Schwarz was the true trait d'union between the Berlin mathematicians and their Italian colleagues. In the early 1870s he had an intensive correspondence with Casaroti and Dini in particular. In his letters to them Schwarz presented the methods and the main results as expounded by Weierstrass in his lectures and seminars. Dini's lectures at the university of Pisa, inspired by the new methods of Weierstrass (and Cantor), were at the basis of his celebrated treatise Fondamenti per la teorica delle funzioni di variabili reali (1878) where Dini acknowledged his debt to Schwarz. From the mid-1860s on, Weierstrass lectured regularly on the theory of analytic functions, the theory of elliptic and Abelian functions and the calculus of variations. This set of lectures, which Weierstrass repeated and refined for nearly 30 years, was never published during his lifetime. The first presentation in Italy of Weierstrass's theory of analytic functions was given in 1880 by Salvatore Pincherle. A student of Dini and Casorati, Pincherle spent one year in Berlin before being appointed in 1880 to a chair of analysis at the University of Bologna. By then Weierstrass's theory of analytic functions was beginning to be taught in Italy.


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Last modified: June 19, 1998