Ciprian Foias

Ciprian Ilie Foiaș (20 July 1933 – 22 March 2020) was a Romanian-American mathematician. He was awarded the Norbert Wiener Prize in Applied Mathematics in 1995, for his contributions in operator theory.
Education and career.
Born in Reșița, Romania, Foias received his doctorate from the University of Bucharest in 1962, under supervision of Miron Nicolescu. He taught at his alma mater (1966–1979), Paris-Sud 11 University (1979–1983), and Indiana University (1983 until retirement). Beginning in 2000, he was a teacher and researcher at Texas A&M University, where he was a Distinguished Professor.
The Foias constant is named after him. Foias is listed as an ISI highly cited researcher.
Together with Sz-Nagy, Foias proved the celebrated Commutant lifting theorem.
He died in Tempe, Arizona on March 22, 2020.