MITTAG-LEFFLER, MAGNUS GSTA

born March 16, 1846, Stockholm, Swed. died July 7, 1927, Stockholm Swedish mathematician who founded the international mathematical journal Acta Mathematica and whose contributions to mathematical research helped advance the Scandinavian school of mathematics. In 1872 Mittag-Leffler became a lecturer in mathematics at the University of Uppsala, Swed., and five years later was appointed professor of mathematics at the University of Helsinki. In 1881 he became professor of mathematics at the University of Stockholm. With the financial patronage of King Oscar II of Sweden, he founded Acta Mathematica in 1882, set up an editorial staff from the four Scandinavian countries, and served as chief editor for 45 years. Mittag-Leffler made numerous contributions to mathematical analysis (concerned with limits and including calculus, analytic geometry, and probability theory). He worked on the general theory of functions, concerning relationships between independent and dependent variables, and in 1875 gave a proof of the French mathematician Augustin-Louis Cauchy's theorem (a theorem that is largely the basis for the modern theory of functions of a complex variable). His best-known work concerned the analytic representation of a one-valued function; this work culminated in the Mittag-Leffler theorem. His estate and his mathematical library now form part of the Mittag-Leffler Mathematical Institute at Djursholm, Swed.