Juliusz Schauder

Juliusz Schauder
Schauder at a topological conference in Moscow, 1935
Born	(1899-09-21)21 September 1899 Lemberg, Austria-Hungary
Died	September 1943(1943-09-00) (aged 43–44) Lwów, Occupied Poland
Alma mater	Jan Kazimierz University
Known for	Schauder basis Schauder fixed-point theorem Schauder estimates Banach–Schauder theorem Faber-Schauder system Leray-Schauder principle Lviv School of Mathematics
Scientific career
Fields	Mathematics
Institutions	Jan Kazimierz University

Juliusz Paweł Schauder ([ˈjulʲjuʂ ˈpavɛw ˈʂau̯dɛr]; 21 September 1899 – September 1943) was a Polish mathematician known for his work in functional analysis, partial differential equations and mathematical physics.

Born on 21 September 1899 in Lwów to a lawyer father of Jewish descent, he was drafted into the Austro-Hungarian Army right after his graduation from school and saw action on the Italian front.^[1] He was captured and imprisoned in Italy. He entered the university in Lwów in 1919 and received his doctorate in 1923. He got no appointment at the university and continued his research while working as teacher at a secondary school. Due to his outstanding results, he obtained a scholarship in 1932 that allowed him to spend several years in Leipzig and, especially, Paris. In Paris he started a very successful collaboration with Jean Leray. Around 1935 Schauder obtained the position of a senior assistant in the University of Lwów. Schauder, along with Stanisław Mazur, was an Invited Speaker of the International Congress of Mathematicians in 1936 in Oslo.^[2]

Schauder was Jewish, and after the invasion of German troops in Lwów 1941 it was impossible for him to continue his work. Even before the Lwów ghetto was established he wrote to Ludwig Bieberbach pleading for his support. Instead, Bieberbach passed his letter to the Gestapo and Schauder was arrested. In his letters to Swiss mathematicians, he wrote that he had important new results, but no paper to write them down. He was executed by the Gestapo, probably in October 1943.^[3]

Most of his mathematical work is in the field of functional analysis, being part of a large Polish group of mathematicians, i.e. the Lwów School of Mathematics. They were pioneers in this area with wide applications in all parts of modern analysis. Schauder is best known for the Schauder fixed-point theorem, which is a major tool to prove the existence of solutions in various problems, the Schauder bases (a generalization of an orthonormal basis from Hilbert spaces to Banach spaces), and the Leray−Schauder principle, a way to establish solutions of partial differential equations from a priori estimates.

The Schauder Medal^[4] is awarded by the J.P. Schauder Center for Nonlinear Studies at the Nicolaus Copernicus University in Toruń, Poland, to individuals for their significant achievements related to topological methods in nonlinear analysis.

• Banach–Schauder theorem
• Schauder basis
• Schauder estimates
• Schauder fixed point theorem
• List of Polish mathematicians

• O'Connor, John J.; Robertson, Edmund F., "Juliusz Schauder", MacTutor History of Mathematics Archive, University of St Andrews
• Ingarden, Roman (1993), "Juliusz Schauder - personal reminiscences", Topological Methods in Nonlinear Analysis, 2 (1): 1–14, doi:10.12775/TMNA.1993.026, Zbl 0795.01027
• Schaerf, H. M. (1993), "My memories of Juliusz Schauder", Topological Methods in Nonlinear Analysis, 2 (1): 15–19, doi:10.12775/TMNA.1993.027, Zbl 0795.01028
• Juliusz P. Schauder Center for Nonlinear Studies