Quelques applications nouvelles de la théorie de fermeture au problème de représentation approchée des fonctions et au problème des moments. [AND] Sur une application de la théorie de fermeture au problème du développement des fonctions arbitraires en séries procédant suivant les polynomes de Tchébicheff.

Petrograd, Académie impériale des Sciences de Petrograd, 1914. Two papers in two. Large 4to (33.5 x 25.1 cm). 133 [74; 59] pp. Original, uniform printed wrappers. = Two important papers on closed sets of orthogonal polynomials by the Russian mathematician Vladimir Andreevich Steklov [here: Wladimir Stekloff] (1864-1928). "Steklov was born in Nizhny Novgorod, Russia. In 1887, he graduated from the Kharkov University, where he was a student of Aleksandr Lyapunov. In 1889-1906 he worked at the Department of Mechanics of this University. He became a full professor in 1896. During 1893-1905 he also taught theoretical mechanics in the Kharkov Technological Institute (now known as Kharkiv Polytechnical Institute). In 1906 he started working at Petersburg University. In 1921 he petitioned for the creation of the Institute of Physics and Mathematics. Upon his death the institute was named after him. The Mathematics Department split from the Institute in 1934. It is now known as Steklov Institute of Mathematics." (Wikipedia). Uncut. Old stamp in the top margin of the title pages; edges a bit frayed, as can be expected; otherwise two very good, clean copies. Much rarer than Steklov's contributions to the Accademia de Lincei.