sentences:  The Institute is run by the Royal Swedish Academy of Sciences on behalf of research societies representing all the Scandinavian countries.The Institute's main building was originally the residence of Magnus Gustaf (Gösta) Mittag-Leffler, who donated it along with his extensive mathematics library.At his death in 1927, however, Mittag-Leffler's fortune was insufficient to set up an active research institute, which began operation only in 1969 under the leadership of Lennart Carleson.