Abraham Plessner (February 13, 1900 – April 18, 1961) was a Russian mathematician. He was born on February 13, 1900, to a Jewish family in

Łódź Łódź, also rendered in English as Lodz, is a city in central Poland and a former industrial centre. It is the capital of Łódź Voivodeship, and is located approximately south-west of Warsaw. The city's coat of arms is an example of canti ...

, which is now in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

. He studied at secondary school where he was taught in Russian, German, and Polish. He studied at the University of Giessen where he studied under

Ludwig Schlesinger Ludwig Schlesinger (Hungarian: Lajos Schlesinger, Slovak Ľudovít Schlesinger), (1 November 1864 – 15 December 1933) was a German mathematician known for the research in the field of linear differential equations. Biography Schlesinger att ...

and Friedrich Engel. He also studied at the

University of Göttingen The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...

and Berlin. He completed his doctorate from the

University of Giessen University of Giessen, official name Justus Liebig University Giessen (german: Justus-Liebig-Universität Gießen), is a large public research university in Giessen, Hesse, Germany. It is named after its most famous faculty member, Justus von L ...

in 1922. Jointly with

Kurt Hensel Kurt Wilhelm Sebastian Hensel (29 December 1861 – 1 June 1941) was a German mathematician born in Königsberg. Life and career Hensel was born in Königsberg, East Prussia (today Kaliningrad, Russia), the son of Julia (née von Adelson) and lan ...

he edited Kronecker's collected works. After completing his doctorate, Plessner worked in

Marburg Marburg ( or ) is a university town in the German federal state (''Bundesland'') of Hesse, capital of the Marburg-Biedenkopf district (''Landkreis''). The town area spreads along the valley of the river Lahn and has a population of approximate ...

where he published a paper containing what is now called Plessner's theorem. It is a theorem concerning the boundary behaviour of functions meromorphic in the unit disk. Plessner submitted his habilitation, the extra post-doctoral qualification needed to lecture at a German university, to the faculty at the University of Giessen. He was denied because he happened to be a Russian citizen. He then moved to Moscow and joined the research group of Nikolai Nikolaevich Luzin at

Moscow State University M. V. Lomonosov Moscow State University (MSU; russian: Московский государственный университет имени М. В. Ломоносова) is a public research university in Moscow, Russia and the most prestigious ...

. Though he left Germany before the Nazi's seized power in 1933, some scholars consider him an early Jewish emigrant from Nazi Germany; his career was negatively impacted by anti-semitism and he was not able to return to Germany, unlike early non-Jewish emigrants such as

Eberhard Hopf Eberhard Frederich Ferdinand Hopf (April 4, 1902 in Salzburg, Austria-Hungary – July 24, 1983 in Bloomington, Indiana, USA) was a mathematician and astronomer, one of the founding fathers of ergodic theory and a pioneer of bifurcation theory who ...

and Wilhelm Maier. One scholar writes that in Plessner's case "the anti-Semitic prejudice was mixed with and partly hidden by concern for their lack of a German citizenship". In 1939, he became a professor at

. He also held a position at the Mathematical Institute of the USSR Academy of Sciences. In 1949, he was dismissed from both posts during the Soviet campaign against "rootless cosmopolitans". Plessner is widely viewed as a founder of the Moscow school of

functional analysis Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. Inner product space#Definition, inner product, Norm (mathematics)#Defini ...

. He faced financial and health problems in his later years. He died on April 18, 1961, in Moscow.

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* * {{DEFAULTSORT:Plessner, Abraham 1900 births 1961 deaths Soviet Jews Soviet mathematicians 20th-century Russian mathematicians Academic staff of Moscow State University Scientists from Łódź Jewish scientists Jewish emigrants from Nazi Germany German emigrants to the Soviet Union