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Max August Zorn (; June 6, 1906 – March 9, 1993) was a German
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, structure, space, models, and change. History On ...
. He was an algebraist, group theorist, and numerical analyst. He is best known for Zorn's lemma, a method used in
set theory Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly concern ...
that is applicable to a wide range of mathematical constructs such as
vector space In mathematics and physics, a vector space (also called a linear space) is a set whose elements, often called '' vectors'', may be added together and multiplied ("scaled") by numbers called ''scalars''. Scalars are often real numbers, but can ...
s, and ordered sets amongst others. Zorn's lemma was first postulated by Kazimierz Kuratowski in 1922, and then independently by Zorn in 1935.


Life and career

Zorn was born in
Krefeld Krefeld ( , ; li, Krieëvel ), also spelled Crefeld until 1925 (though the spelling was still being used in British papers throughout the Second World War), is a city in North Rhine-Westphalia, Germany. It is located northwest of Düsseldorf, ...
,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
. He attended the
University of Hamburg The University of Hamburg (german: link=no, Universität Hamburg, also referred to as UHH) is a public research university in Hamburg, Germany. It was founded on 28 March 1919 by combining the previous General Lecture System ('' Allgemeines Vo ...
. He received his
PhD PHD or PhD may refer to: * Doctor of Philosophy (PhD), an academic qualification Entertainment * '' PhD: Phantasy Degree'', a Korean comic series * '' Piled Higher and Deeper'', a web comic * Ph.D. (band), a 1980s British group ** Ph.D. (Ph.D. al ...
in April 1930 for a thesis on alternative algebras. He published his findings in '' Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg''. Zorn showed that
split-octonion In mathematics, the split-octonions are an 8-dimensional nonassociative algebra over the real numbers. Unlike the standard octonions, they contain non-zero elements which are non-invertible. Also the signatures of their quadratic forms differ: t ...
s could be represented by a mixed-style of matrices called Zorn's vector-matrix algebra. Max Zorn was appointed to an assistant position at the University of Halle. However, he did not have the opportunity to work there for long as he was forced to leave Germany in 1933 because of policies enacted by the
Nazi Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in ...
s. According to grandson Eric, " axspoke with a raspy, airy voice most of his life. Few people knew why, because he only told the story after significant prodding, but he talked that way because pro-Hitler thugs who objected to his politics, had battered his throat in a 1933 street fight." Zorn immigrated to the United States and was appointed a Sterling Fellow at
Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the w ...
. While at Yale, Zorn wrote his paper "A Remark on Method in Transfinite Algebra" that stated his Maximum Principle, later called Zorn's lemma. It requires a set that contains the union of any chain of
subset In mathematics, set ''A'' is a subset of a set ''B'' if all elements of ''A'' are also elements of ''B''; ''B'' is then a superset of ''A''. It is possible for ''A'' and ''B'' to be equal; if they are unequal, then ''A'' is a proper subset of ...
s to have one chain not contained in any other, called the maximal element. He illustrated the principle with applications in ring theory and field extensions. Zorn's lemma is an alternative expression of the
axiom of choice In mathematics, the axiom of choice, or AC, is an axiom of set theory equivalent to the statement that ''a Cartesian product of a collection of non-empty sets is non-empty''. Informally put, the axiom of choice says that given any collection ...
, and thus a subject of interest in
axiomatic set theory Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly concern ...
. In 1936 he moved to UCLA and remained until 1946. While at UCLA Zorn revisited his study of alternative rings and proved the existence of the nilradical of certain alternative rings. According to Angus E. Taylor, Max was his most stimulating colleague at UCLA. In 1946 Zorn became a professor at
Indiana University Indiana University (IU) is a system of public universities in the U.S. state of Indiana. Campuses Indiana University has two core campuses, five regional campuses, and two regional centers under the administration of IUPUI. *Indiana Universi ...
, where he taught until retiring in 1971. He was thesis advisor for Israel Nathan Herstein. Zorn died in
Bloomington, Indiana Bloomington is a city in and the county seat of Monroe County in the central region of the U.S. state of Indiana. It is the seventh-largest city in Indiana and the fourth-largest outside the Indianapolis metropolitan area. According to the Mo ...
, in March 1993, of congestive heart failure, according to his obituary in ''
The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
''.


Family

Max Zorn married Alice Schlottau and they had one son, Jens, and one daughter, Liz. Jens (born June 19, 1931) is an emeritus professor of physics at the
University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...
and an accomplished sculptor. Max Zorn's grandson Eric Zorn was a columnist for the ''
Chicago Tribune The ''Chicago Tribune'' is a daily newspaper based in Chicago, Illinois, United States, owned by Tribune Publishing. Founded in 1847, and formerly self-styled as the "World's Greatest Newspaper" (a slogan for which WGN radio and television ar ...
'' from 1986 until 2021; after retirement Eric Zorn started a Substack newsletter titled "The Picayune Sentinel", named after the mathematics newsletter that Max Zorn had distributed during his years at Indiana University. Max's great grandson, Alexander Wolken Zorn, received a PhD in mathematics from the University of California Berkeley in 2018.


See also

* Artin–Zorn theorem * Zorn ring


References

* Steve Carlson (2009
Max Zorn: World Renowned Mathematician and Member Indiana MAA Section
, from Mathematics Association of America . * Darrell Haile (1993
On Max Zorn's Contributions to Mathematics
(includes John Ewing, "Zorn's Lemma"), from Memorial Conference at Indiana University, June 1993.


External links

* * {{DEFAULTSORT:Zorn, Max August 20th-century American mathematicians 20th-century German mathematicians Set theorists Algebraists Numerical analysts Indiana University faculty German emigrants to the United States 1906 births 1993 deaths People from Krefeld Deaths from congestive heart failure University of Hamburg alumni University of California, Los Angeles faculty Yale University fellows