János Dezső Aczél (; 26 December 1924 – 1 January 2020), also known as John Aczel, was a Hungarian-

Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...

mathematician, who specialized in

functional equations In mathematics, a functional equation is, in the broadest meaning, an equation in which one or several functions appear as unknowns. So, differential equations and integral equations are functional equations. However, a more restricted meaning ...

and information theory.

Professional career

Aczél earned a doctorate in mathematical analysis from the

University of Budapest A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...

, and held positions at the

University of Cologne The University of Cologne (german: Universität zu Köln) is a university in Cologne, Germany. It was established in the year 1388 and is one of the most prestigious and research intensive universities in Germany. It was the sixth university to ...

, Kossuth University,

University of Miskolc The University of Miskolc (before 1990: ''Technical University of Heavy Industry'') is the largest university of Northern Hungary. Location Most of the buildings can be found in Egyetemváros ("University Town"), a part of the city of Miskolc. I ...

, and

University of Szeged , mottoeng = Truth. Bravery. Freedom. , established = , type = Public research university , founder = Emperor Franz Joseph I , affiliation = European University Association, Science Without Borders, Confucius Institute , budget = US$220 m ...

.Biography as a speaker at the Marschak Colloquium at UCLA
1999, accessed 25 January 2013. He joined the

University of Waterloo The University of Waterloo (UWaterloo, UW, or Waterloo) is a public research university with a main campus in Waterloo, Ontario, Canada. The main campus is on of land adjacent to "Uptown" Waterloo and Waterloo Park. The university also operates ...

faculty in 1965, eventually becoming Distinguished Professor in the Department of Pure Mathematics. He was the founder of the journal ''

Aequationes Mathematicae ''Aequationes Mathematicae'' is a mathematical journal. It is primarily devoted to functional equations, but also publishes papers in dynamical systems, combinatorics, and geometry. As well as publishing regular journal submissions on these topic ...

'', first published in 1968, and remained its honorary editor-in-chief.

Awards and honors

Aczél held honorary degrees from the

University of Karlsruhe The Karlsruhe Institute of Technology (KIT; german: Karlsruher Institut für Technologie) is a public research university in Karlsruhe, Germany. The institute is a national research center of the Helmholtz Association. KIT was created in 2009 w ...

, the

University of Graz The University of Graz (german: link=no, Karl-Franzens-Universität Graz, ), located in Graz, Austria, is the largest and oldest university in Styria, as well as the second-largest and second-oldest university in Austria. History The univers ...

, and the

University of Silesia in Katowice The University of Silesia in Katowice ( pl, Uniwersytet Śląski w Katowicach, UŚ) is an autonomous state-run university in Silesia Province, Katowice, Poland. The university offers higher education and research facilities. It offers undergrad ...

. In 1971, he was elected a fellow of the Royal Society of Canada. He was the 1988 winner of the

Santiago Ramón y Cajal Santiago Ramón y Cajal (; 1 May 1852 – 17 October 1934) was a Spanish neuroscientist, pathologist, and histologist specializing in neuroanatomy and the central nervous system. He and Camillo Golgi received the Nobel Prize in Physiology or Me ...

Medal. In 1990, he became an external member of the Hungarian Academy of Sciences,Member listing
Hungarian Academy of Sciences, accessed 25 January 2013. and, in 2004, he was honored by the academy as one of the "big five" most distinguished Hungarian mathematicians. The other honorees were John Horvath, Steven Gaal,

Ákos Császár Ákos Császár ( hu, Császár Ákos, ) (26 February 1924, Budapest – 14 December 2017, Budapest) was a Hungarian mathematician, specializing in general topology and real analysis. He discovered the Császár polyhedron, a nonconvex polyhedr ...

and

László Fuchs László Fuchs (born June 24, 1924) is a Hungarian-born American mathematician, the Evelyn and John G. Phillips Distinguished Professor Emeritus in Mathematics at Tulane University.

.Tribute to the achievements of five outstanding Hungarian mathematicians
Department of Mathematical Sciences of the Hungarian Academy of Sciences In 2008, he became an honorary member of the

Hamburg Mathematical Society The Hamburg Mathematical Society (german: Mathematische Gesellschaft in Hamburg) is a learned society concerned with mathematics and located in the German city of Hamburg. It was founded in 1690 by Heinrich Meissner as the "Kunstrechnungsübende S ...

, the oldest active mathematical society in the world. In 2004, he won the Kampé de Fériet Award of the annual Information Processing and Management of Uncertainty conference, "for his pioneering work on the theory of functional equations, with applications in many fields, such as information measures, index numbers, group decision making, aggregation, production functions, laws of science, theory of measurement and utility theory." Issues of the journal ''Aequationes Mathematicae'' were dedicated to Aczél in 1999, 2005, and 2010, in honor of his 75th, 80th, and 85th birthdays. He died six days after his 95th birthday on 1 January 2020..

Selected publications

Articles

* * * * *

Books

Aczél was the author or co-author of: *. *. Previously published in German as ''Vorlesungen über Funktionalgleichungen und ihre Anwendungen'' (Birkhäuser, 1961). *. *. *.Review of ''Functional equations in several variables'' by K. Lajkó, . He was the editor of: * (1st edition 1984) * (1st edition 1995)

References

External links

* Aczél'
homepage
at the Hungarian Academy of Sciences. *
Author profile
in the database

zbMATH zbMATH Open, formerly Zentralblatt MATH, is a major reviewing service providing reviews and abstracts for articles in pure and applied mathematics, produced by the Berlin office of FIZ Karlsruhe – Leibniz Institute for Information Infrastruct ...

{{DEFAULTSORT:Aczel, Janos 1924 births 2020 deaths 20th-century Hungarian mathematicians Canadian mathematicians Hungarian emigrants to Canada Naturalized citizens of Canada Members of the Hungarian Academy of Sciences University of Waterloo faculty Fellows of the Royal Society of Canada Mathematicians from Budapest