Issai Schur (January 10,1875 – January 10,1941) was a mathematician who worked in Germany for most of his life.He studied at Berlin.He obtained his doctorate in 1901,became lecturer in 1903 and,after a stay at Bonn,professor in 1919.
He considered himself German rather than Jewish,even though he had been born in the Russian Empire in what is now Belarus,and brought up partly in Latvia.For this reason he declined invitations to leave Germany for the United States and Britain in 1934.Nevertheless he was dismissed from his chair in 1935 and,at the instigation of Ludwig Bieberbach (who had previously sympathised with Schur regarding his treatment at the hands of the Nazis),he was forced to resign from the Prussian Academy in 1938.Schur eventually emigrated to Palestine in 1939,and lived his final years in poverty.He died in Tel Aviv on his 66th birthday.
As a student of Frobenius,he worked on group representations (the subject with which he is most closely associated),but also in combinatorics and number theory and even theoretical physics.He is perhaps best known today for his result on the existence of the Schur decomposition and for his work on group representations (Schur's lemma).
Schur had a number of students,including Richard Brauer,B.H.Neumann,Heinz Prüfer,and Richard Rado.His lectures were very popular with students.[1] He was elected to the Academy of Sciences of the USSR as a foreign corresponding member in 1929.
Schur published under the name of both I.Schur,and J.Schur,the latter especially in Journal für die reine und angewandte Mathematik.This has led to some confusion.