Erhard Schmidt (13 January 1876 – 6 December 1959) was a Baltic German mathematician whose work significantly influenced the direction of mathematics in the twentieth century.
His doctoral dissertation was entitled Entwickelung willkürlicher Funktionen nach Systemen vorgeschriebener and was a work on integral equations.
Ernst Zermelo credited conversations with Schmidt for the idea and method for his classic 1904 proof of the Well-ordering theorem from an "Axiom of choice", which has become an integral part of modern set theory.
[2] During World War II Schmidt held positions of authority at the University of Berlin and had to carry out various Nazi resolutions against the Jews—a job that he apparently did not do well, since he was criticized at one point for not understanding the "Jewish question".
[2] Schmidt was, however, a conservative and a nationalist, and defended Hitler after Kristallnacht, telling Issai Schur that "Suppose we had to fight a war to rearm Germany, unite with Austria, liberate the Saar and the German part of Czechoslovakia.