Family Story

The famous mathematical geniuses of Győr – the Riesz brothers

Soccer player Öcsi Puskás’ adventure with Professor Frigyes Riesz

Frigyes Riesz

Frigyes (Győr, 22 January 1880 – Budapest, 28 February 1956) Hungarian mathematician, university professor, member of the Hungarian Academy of Sciences, brother of mathematician Marcell Riesz. The two sons were born to the Jewish doctor Ignác Riesz and Szidónia Nagel of Győr.

The house where the famous mathematician Riesz brothers, Frigyes and Marcell, were born. (Győr, corner of Kazinczy u. and Jedlik Ányos út) © kozterkep/mapublic

His key insight is that, by defining the operations of addition, multiplication by a number and scalar multiplication between functions in a suitable way, a wide class of functions behave in the same way as vectors. Recognising the importance of this idea, Riesz became, together with Maurice René Fréchet and Stefan Banach, the founder of functional analysis. Functional analysis is a comprehensive theory combining the methods of algebra, analysis and geometry. His best-known result is the Riesz-Fischer theorem, which is well known in real-valued functional theory.

He studied at the University of Zurich (1897-99), the University of Budapest (1899-1901) and the University of Göttingen (1901-02). He taught for a short time at a secondary school, then moved to the Franz Joseph University of Kolozsvár, which moved to Szeged in 1921 following the Treaty of Trianon. Riesz was head professor of the Mathematical Institute at the University of Szeged, and from 1929 to 1946 of the Bolyai Institute.

Frigyes Riesz in university regalia

János Neumann thought it would be good if the world-famous mathematical centre established in Szeged – Riesz, Alfréd Haar, Béla Kerékjártó – stayed together. There is no doubt that around 1930, Szeged was the place in the world where classical functional theory and functional analysis could be studied to the highest standards. It is no coincidence that Marshall Stone, professor at Harvard University and author of the first monograph on functional analysis, sent his colleague to Szeged to study.

Riesz also gave lectures on Functional Operations, followed by The Theory of Hilbert Spaces and Integral Equations. All these were combined into a book by the end of the 1940s, and a comprehensive textbook on functional analysis was born, with unprecedented success. Of particular importance is the journal Acta Scientiarum Mathematicarum, which he launched with Alfred Haar and which is still a world-class journal in mathematics.

When the Franz Joseph University moved back to Kolozsvár on 19 October 1940, Riesz did not go there because of his old age, but asked to be transferred to the newly founded Miklós Horthy University in Budapest and continued to head the Bolyai Institute. From 1946 until his death, he was head of department at the Budapest University of Sciences (then Pázmány Péter University, later Eötvös Loránd University as from 1950).

Even in the most difficult times, Frigyes Riesz received exceptional treatment for his outstanding scientific achievements and his high international profile. In November 1943, for example, he was granted a service passport, permission to leave the country and travel supplies for lectures in Geneva. Frigyes Riesz sewed on the humiliating yellow star, but always wore a top coat … He was forced to retire in July 1944, but in August 1944 (!) he regained his job together with several other professors of Jewish origin.

Memorial plaque on the parental home © kozterkep/mapublic

Marcell’s descendants living in Sweden were present at the unveiling of the brothers’ memorial plaque in Győr. They also visited the office of the Jewish community in Győr, where they looked up the brothers’ birth records in the register of births (according to the office).

Riesz’s life was filled with mathematics. Early spring 1954, Prague, the airport of the Czechoslovak capital. An elderly gentleman settles into one of the armchairs, two young men sit down near him. The older man is reading. In the meantime, because he hears Hungarian words, he turns to the young people with interest, wondering where they are going. We’re going to Amsterdam for a friendly match,” says one of them.

Puskás and Lóránt rejoice together

It soon becomes clear: all three are from Pest, there are no direct flights from there, so they fly on from Prague, the old man to Paris for a conference, the boys via Brussels to Amsterdam. The match will be there. “But what match?” asks the old gentleman. “Well, what else, soccer!” replies one of them, self-consciously, in a slightly raised voice, and adds, in case the uninformed questioner does not understand: football, that’ s all! Then he points to his partner: “This is Gyula Lóránt, the many times national team midfielder, you may have heard of him. And I am Puskás”.

Ferenc Puskás, the world-famous football player who did not know Frigyes Riesz
Frigyes Riesz, the world-famous mathematician who did not know Lajos Puskás

The elderly gentleman nods with a smile, introduces himself, ponders a bit, takes a puff on his pipe, and then comes another question for Puskás: “And you are a football player?”

(The story is told by János Varga, a mathematics teacher from Székesfehérvár.)

Riesz Marcell

Marcell (Győr, 16 November 1886 – Lund (Sweden), 4 September 1969), university professor, younger brother of Frigyes, also a mathematician.

Riesz Marcell professzor, Fejér Lipót tanítványa

He received his doctorate from Lipót Fejér at the University of Budapest. He moved to Sweden in 1911 and taught at Stockholm University from 1911 to 1925. From 1926 to 1952 he was professor at the University of Lund. After his retirement he spent 10 years at American universities. He returned to Lund in 1962 and died there in 1969.

He was elected a member of the Royal Swedish Academy of Sciences in 1936.

Marcell Riesz worked on trigonometric series. He introduced the Riesz Function and, together with his brother, proved the theorem known since then as the Riesz Brothers’ Theorem. In the 1940s and 1950s Riesz worked on Clifford Algebras.

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Gábor I. Kovács: The fate of Hungarian Jewish university professors and those of Jewish-origin before and during the Holocaust from 1930 to 1945 (article), 2015. Based on the Database of Hungarian university professors I. Jewish university professors and those of Jewish-origin – Historical Elite Research, Budapest, Publishing House Eötvös: 2012. p. 172