Frederic Riesz

Frigyes (Frederic) Riesz was a Hungarian mathematician, a founder of functional analysis, who introduced Lp spaces, proved the Riesz representation theorem and the Riesz–Fischer theorem, and did fundamental work on compact operators and ergodic theory. He came from a Hungarian Jewish family and co-founded, with Alfréd Haar, the influential Szeged mathematics school and its journal. His ideas underpin much of modern analysis and quantum theory's mathematical framework.