Person: Riesz, Frigyes
Riesz was a founder of functional analysis and his work has many important applications in physics.
Mathematical Profile (Excerpt):
- Frigyes (or Frederic in German) Riesz studied at Budapest.
- Riesz was a founder of functional analysis and his work has many important applications in physics.
- In 1907 and 1909 Riesz produced representation theorems for functional on quadratic Lebesgue integrable functions and, in the second paper, in terms of a Stieltjes integral.
- A satisfactory theory of series of orthonormal functions only became possible after the invention of the Lebesgue integral and this theory was largely the work of Riesz.
- Riesz's work of 1910 marks the start of operator theory.
- Riesz was appointed to a chair in Kolozsvár in Hungary in 1911.
- In Szeged in 1922 Riesz set up the János Bolyai Mathematical Institute in a joint venture with Haar.
- Riesz became editor of the newly founded journal of the Institute Acta Scientiarum Mathematicarum which quickly became a major source of mathematics.
- Riesz was to publish many papers in this journal, the first in 1922 being on Egorov's theorem on linear functionals.
- In 1945 Riesz was appointed to the chair of mathematics in the University of Budapest.
- Many of Riesz's fundamental findings in functional analysis were incorporated with those of Banach.
- His theorem, now called the Riesz-Fischer theorem, which he proved in 1907, is fundamental in the Fourier analysis of Hilbert space.
- Riesz made many contributions to other areas including ergodic theory where he gave an elementary proof of the mean ergodic theorem in 1938.
- The more leisurely mastership of F Riesz's style, whether he writes in his native Hungarian, or in French or German, conveys such pleasure and is to the older mathematician a nostalgic remainder of what we are in danger to lose.
- With it, and with all his other work, will live the memory of Frederic Riesz as a great and fertile mathematician for long in the history of our art.
- Riesz received many honours for his work.
Born 22 January 1880, Györ, Austria-Hungary (now Hungary). Died 28 February 1956, Budapest, Hungary.
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Tags relevant for this person:
Origin Hungary, Physics, Topology
Thank you to the contributors under CC BY-SA 4.0! 
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- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
