Børge Jessen

Børge Christian Jessen ( born June 19, 1907 in Copenhagen, † March 20, 1993 ) was a Danish mathematician.

Jessen studied from 1925 to 1929 at the University of Copenhagen with Harald Bohr. In 1929, he was with a Carlsberg Scholarship in Hungary at the University of Szeged in Frigyes Riesz and Alfréd hair and then a semester at the University of Göttingen with David Hilbert and Edmund Landau. In 1930 he received his doctorate in Copenhagen and became a lecturer at the Royal Veterinary College. 1933/34, and in 1949 he was at the Institute for Advanced Study, and also in the 1930s, often in Paris, Cambridge, Harvard University and Yale University. In 1935, he was the successor of Tommy BONNESEN professor of descriptive geometry at the University of Copenhagen (then Polytechnic educational institution ). From 1942 he was a follower of John Hjelmslev professor at the University of Copenhagen, where he retired in 1977. At the University of Copenhagen he was in the 1960s, one of the founders of the Hans Christian Ørsted Institute, which houses the Departments of Mathematics, Chemistry and partly of physics.

Jessen dealt with measure theory, integration theory and other aspects of functional analysis as the theory of Hilbert spaces and of almost periodic functions, which he applied with Harald Bohr to the theory of the Riemann zeta function. In the U.S., he worked with Salomon Bochner, Paul Halmos, George Mackey and Aurel Wintner. He also worked with Paul Erdős on graph theory and combinatorial geometry, including through the decomposition of equality of polyhedra, one of the Hilbert problems, also on the Max Dehn and Hugo Hadwiger worked. With Erik Sparre Andersen he published in 1948 a Konvergenztheorem for martingales, also called Andersen - Jessen theorem. The roots also go back to his dissertation.

He in the founding committee of the International Mathematical Union, which was founded in 1951 and had its headquarters in Copenhagen. 1930 to 1942 he was secretary of the Danish Mathematical Society from 1973 and whose honorary member. A Graduate Prize of the Danish Mathematical Society is named after him. In 1954 he gave a plenary lecture at the International Congress of Mathematicians (ICM ) in Amsterdam, entitled Some Aspects of the Theory of Almost Periodic Functions. He was president of the Carlsberg Foundation and the Council of the Rask - Ørsted Society.