Nachman Aronszajn (26 July 1907 – 5 February 1980[1]) was a Polish American mathematician.
Aronszajn's main field of study was mathematical analysis, where he systematically developed the concept of reproducing kernel Hilbert space.
An Ashkenazi Jew, Aronszajn received his Ph.D. from the University of Warsaw, in 1930, in Poland.
He also received a Ph.D. from Paris University, in 1935; this time Maurice Fréchet was his thesis advisor.
He joined the Oklahoma State University faculty, but moved to the University of Kansas in 1951 with his colleague Ainsley Diamond after Diamond, a Quaker, was fired for refusing to sign a newly instituted loyalty oath.