Frigyes Riesz ( hu, Riesz Frigyes, , sometimes spelled as Frederic; 22 January 1880 – 28 February 1956) was a

/ref>

Pál Medgyessy's entry

in ''Tudósnaptár'' ("Calendar of Scientists")

HungarianHungarian may refer to:
* Hungary, a country in Central Europe
* Kingdom of Hungary, state of Hungary, existing between 1000 and 1946
* Hungarians, ethnic groups in Hungary
* Hungarian algorithm, a polynomial time algorithm for solving the assignmen ...

Eberhard Zeidler: Nonlinear Functional Analysis and Its Applications: Linear monotone operators. Springer, 199/ref>

mathematician
A mathematician is someone who uses an extensive knowledge of mathematics
Mathematics (from Greek: ) includes the study of such topics as numbers ( and ), formulas and related structures (), shapes and spaces in which they are contained ( ...

who made fundamental contributions to functional analysis
200px, One of the possible modes of vibration of an idealized circular drum head. These modes are eigenfunctions of a linear operator on a function space, a common construction in functional analysis.
Functional analysis is a branch of mathemat ...

, as did his younger brother Marcel Riesz
Marcel Riesz ( hu, Riesz Marcell ; 16 November 1886 – 4 September 1969) was a Hungarian mathematician
A mathematician is someone who uses an extensive knowledge of mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study ...

.
Life and career

He was born into aJewish
Jews ( he, יְהוּדִים ISO 259-2ISO
The International Organization for Standardization (ISO; ) is an international standard
are technical standards developed by international organizations (intergovernmental organizations), suc ...

family in Győr
Győr ( , ; german: Raab, links=no; names in other languages) is the most important city of northwest Hungary
Hungary ( hu, Magyarország ) is a country in Central Europe. It borders Slovakia to the north, Ukraine to the northeast, Romani ...

, Austria-Hungary
Austria-Hungary, often referred to as the Austro-Hungarian Empire or the Dual Monarchy, was a and in between 1867 and 1918. It was formed with the and was dissolved following its defeat in the .
At its core was the which was a between th ...

and died in Budapest
Budapest (, ) is the capital and the of , and the in the by population within city limits. The city has an estimated population of 1,752,286 over a land area of about . Budapest is both a and , and forms the centre of the , which has an ar ...

, Hungary
Hungary ( hu, Magyarország ) is a in . Spanning of the , it is bordered by to the north, to the northeast, to the east and southeast, to the south, and to the southwest and to the west. Hungary has a population of 10 million, mostl ...

. Between 1911 and 1919 he was a professor at the Franz Joseph University
Royal Hungarian Franz Joseph University ( hu, Magyar Királyi Ferenc József Tudományegyetem) was the second University#Modern universities, modern university in the Lands of the Crown of Saint Stephen, Hungarian realm of the Austria-Hungary, Au ...

in Kolozsvár, Austria-Hungary. The post-WW1 Treaty of Trianon
's pacifist speech for military officers, and declaration of Hungarian self-disarmament on 2 November 1918.
The Treaty of Trianon (french: Traité de Trianon, hu, Trianoni békeszerződés) was prepared at the Paris Peace Conference, 1919 ...

transferred former Austro-Hungarian territory including Kolozsvár to the Kingdom of Romania
The Kingdom of Romania ( ro, Regatul României) was a constitutional monarchy
A constitutional monarchy, parliamentary monarchy, or democratic monarchy is a form of monarchy in which the monarch exercises his authority in accordance with a co ...

, whereupon Kolozsvár's name changed to Cluj
; hu, kincses város)
, official_name=Cluj-Napoca
, image_skyline=
, subdivision_type1 = County
A county is a geographical region of a country used for administrative or other purposesChambers Dictionary, L. Brookes (ed.), 2005, Chambers ...

and the University of Kolozsvár moved to Szeged
Szeged ( , ; see also #Etymology, other alternative names) is List of cities and towns of Hungary#Largest cities in Hungary, the third largest city of Hungary, the largest city and regional centre of the Southern Great Plain and the county seat ...

, Hungary, becoming the University of Szeged
The University of Szeged ( hu, Szegedi Tudományegyetem, ) is a large research university in Hungary
Hungary ( hu, Magyarország ) is a country in Central Europe. It borders Slovakia to the north, Ukraine to the northeast, Romania to the ...

. Then, Riesz was the rector
Rector (Latin for the member of a vessel's crew who steers) may refer to:
Style or title
*Rector (ecclesiastical), a cleric who functions as an administrative leader in some Christian denominations
*Rector (academia), a senior official in an educ ...

and a professor at the University of Szeged, as well as a member of the Hungarian Academy of SciencesHungarian may refer to:
* Hungary
Hungary ( hu, Magyarország ) is a country in Central Europe. It borders Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and Slovenia to the so ...

. and the Polish Academy of Learning
The Polish Academy of Arts and Sciences or Polish Academy of Learning ( pl, Polska Akademia Umiejętności), headquartered in Kraków
Kraków (), also written in English as Krakow and traditionally known as Cracow, is the second-largest and ...

. He was the older brother of the mathematician Marcel Riesz
Marcel Riesz ( hu, Riesz Marcell ; 16 November 1886 – 4 September 1969) was a Hungarian mathematician
A mathematician is someone who uses an extensive knowledge of mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study ...

.
Riesz did some of the fundamental work in developing functional analysis
200px, One of the possible modes of vibration of an idealized circular drum head. These modes are eigenfunctions of a linear operator on a function space, a common construction in functional analysis.
Functional analysis is a branch of mathemat ...

and his work has had a number of important applications in physics. He established the spectral theoryIn mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ha ...

for bounded symmetric operators in a form very much like that now regarded as standard. He also made many contributions to other areas including ergodic theory, topology and he gave an elementary proof of the mean ergodic theorem.
Riesz founded the Acta Scientiarum Mathematicarum journal together with Alfréd Haar.
He had an uncommon method of giving lectures: he entered the lecture hall with an assistant and a docent. The docent then began reading the proper passages from Riesz's handbook and the assistant wrote the appropriate equations on the blackboard—while Riesz himself stood aside, nodding occasionally.
The Swiss-American mathematician Edgar Lorch spent 1934 in Szeged working under Riesz and wrote a reminiscence about his time there, including his collaboration with Riesz.
The corpus of his bibliography was compiled by the mathematician Pál Medgyessy.in ''Tudósnaptár'' ("Calendar of Scientists")

Publications

*See also

*Proximity space *Rising sun lemma *Denjoy–Riesz theorem *F. and M. Riesz theorem *Riesz representation theorem *Riesz-Fischer theorem *Approximately finite-dimensional C*-algebra#Riesz groups, Riesz groups *Riesz's lemma *Riesz sequence *Riesz space *Radon-Riesz propertyReferences

External links

* * * * {{DEFAULTSORT:Riesz, Frigyes 1880 births 1956 deaths University of Szeged faculty 19th-century Hungarian mathematicians 20th-century Hungarian mathematicians Mathematical analysts Functional analysts Operator theorists Mathematicians from Budapest Members of the Hungarian Academy of Sciences Burials at Kerepesi Cemetery Franz Joseph University faculty Rectors of the Franz Joseph University Austro-Hungarian mathematicians