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Roger Apéry (; 14 November 1916,
Rouen Rouen (, ; or ) is a city on the River Seine, in northwestern France. It is in the prefecture of Regions of France, region of Normandy (administrative region), Normandy and the Departments of France, department of Seine-Maritime. Formerly one ...
– 18 December 1994,
Caen Caen (; ; ) is a Communes of France, commune inland from the northwestern coast of France. It is the Prefectures in France, prefecture of the Departments of France, department of Calvados (department), Calvados. The city proper has 105,512 inha ...
) was a Greek-French
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
most remembered for Apéry's theorem, which states that is an
irrational number In mathematics, the irrational numbers are all the real numbers that are not rational numbers. That is, irrational numbers cannot be expressed as the ratio of two integers. When the ratio of lengths of two line segments is an irrational number, ...
. Here, denotes the
Riemann zeta function The Riemann zeta function or Euler–Riemann zeta function, denoted by the Greek letter (zeta), is a mathematical function of a complex variable defined as \zeta(s) = \sum_^\infty \frac = \frac + \frac + \frac + \cdots for and its analytic c ...
.


Biography

Apéry was born in
Rouen Rouen (, ; or ) is a city on the River Seine, in northwestern France. It is in the prefecture of Regions of France, region of Normandy (administrative region), Normandy and the Departments of France, department of Seine-Maritime. Formerly one ...
in 1916 to a French mother and
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
father. His childhood was spent in
Lille Lille (, ; ; ; ; ) is a city in the northern part of France, within French Flanders. Positioned along the Deûle river, near France's border with Belgium, it is the capital of the Hauts-de-France Regions of France, region, the Prefectures in F ...
until 1926, when the family moved to
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
, where he studied at the Lycée Ledru-Rollin and the
Lycée Louis-le-Grand The Lycée Louis-le-Grand (), also referred to simply as Louis-le-Grand or by its acronym LLG, is a public Lycée (French secondary school, also known as sixth form college) located on Rue Saint-Jacques (Paris), rue Saint-Jacques in central Par ...
. He was admitted at the
École normale supérieure École or Ecole may refer to: * an elementary school in the French educational stages normally followed by Secondary education in France, secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing i ...
in 1935. His studies were interrupted at the start of
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
; he was mobilized in September 1939, taken
prisoner of war A prisoner of war (POW) is a person held captive by a belligerent power during or immediately after an armed conflict. The earliest recorded usage of the phrase "prisoner of war" dates back to 1610. Belligerents hold prisoners of war for a ...
in June 1940, repatriated with pleurisy in June 1941, and hospitalized until August 1941. He wrote his doctoral thesis in
algebraic geometry Algebraic geometry is a branch of mathematics which uses abstract algebraic techniques, mainly from commutative algebra, to solve geometry, geometrical problems. Classically, it studies zero of a function, zeros of multivariate polynomials; th ...
under the direction of Paul Dubreil and René Garnier in 1947. In 1947 Apéry was appointed
Maître de conférences The following summarizes basic academic ranks in the France, French higher education system. Most academic institutions are state-run and most academics with permanent positions are French Civil Service, civil servants, and thus are Academic tenur ...
(lecturer) at the
University of Rennes The University of Rennes (French: ''Université de Rennes'') is a public university, public research university located in Rennes, Upper Brittany, France. Originally founded in 1460, the university was split into two universities in 1970: Univers ...
. In 1949 he was appointed Professor at the University of Caen, where he remained until his retirement. In 1979 he published an unexpected proof of the
irrationality Irrationality is cognition, thinking, talking, or acting without rationality. Irrationality often has a negative connotation, as thinking and actions that are less useful or more illogical than other more rational alternatives. The concept o ...
of , which is the sum of the inverses of the cubes of the
positive integer In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positiv ...
s. An indication of the difficulty is that the corresponding problem for other odd powers remains unsolved. Nevertheless, many mathematicians have since worked on the so-called Apéry sequences to seek alternative proofs that might apply to other odd powers ( Frits Beukers, Alfred van der Poorten, Marc Prévost, Keith Ball, Tanguy Rivoal, Wadim Zudilin, and others). Apéry was active in politics and for a few years in the 1960s was president of the Calvados
Radical Party of the Left The Radical Party of the Left (, PRG) is a social-liberal political party in France. A party in the Radical tradition, since 1972 the PRG has been a close ally of the major party of the centre-left in France, the Socialist Party (, PS). Af ...
. He abandoned politics after the reforms instituted by Edgar Faure after the 1968 revolt, when he realised that university life was running against the tradition he had always upheld.


Personal life

Apéry married in 1947 and had three sons, including mathematician François Apéry. His first marriage ended in divorce in 1971. He then remarried in 1972 and divorced in 1977. In 1994, Apéry died from
Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...
after a long illness in
Caen Caen (; ; ) is a Communes of France, commune inland from the northwestern coast of France. It is the Prefectures in France, prefecture of the Departments of France, department of Calvados (department), Calvados. The city proper has 105,512 inha ...
. He was buried next to his parents at the
Père Lachaise Cemetery Père Lachaise Cemetery (, , formerly , ) is the largest cemetery in Paris, France, at . With more than 3.5 million visitors annually, it is the most visited necropolis in the world. Buried at Père Lachaise are many famous figures in the ...
in Paris. His tombstone has a mathematical inscription stating his theorem. : 1 + \frac + \frac + \frac + \cdots \neq \frac


See also

*
Apéry's constant In mathematics, Apéry's constant is the infinite sum of the reciprocals of the positive integers, cubed. That is, it is defined as the number : \begin \zeta(3) &= \sum_^\infty \frac \\ &= \lim_ \left(\frac + \frac + \cdots + \f ...
*
Basel problem The Basel problem is a problem in mathematical analysis with relevance to number theory, concerning an infinite sum of inverse squares. It was first posed by Pietro Mengoli in 1650 and solved by Leonhard Euler in 1734, and read on 5 December 1735 ...


External links

* * {{DEFAULTSORT:Apéry, Roger 1916 births 1994 deaths École Normale Supérieure alumni Scientists from Rouen Academic staff of the University of Caen Normandy French number theorists French people of Greek descent 20th-century French mathematicians French prisoners of war in World War II Academic staff of the University of Rennes Lycée Louis-le-Grand alumni Deaths from Parkinson's disease in France Burials at Père Lachaise Cemetery French military personnel of World War II