佐恩引理的发现

佐恩引理的发现

       ​ 对于构建超实数系统，如何理解佐恩引理及其应用是第一道“门槛儿”。我们必须知难而上，而不能退缩不前。

    ​    ​佐恩（1906-1993）简历：生于德国，24岁取得数学博士学位，后移居美国定居。1935年，佐恩29岁时发现了选择公理（AC）的另一种表现形式。

    ​    ​尊重数学知识的创造，必须尊重数学家，了解数学家，懂得他们的主要工作。

​　　袁萌   陈启清  9月4日

附：Max August Zorn简介

Born June 6, 1906
Krefeld, Rhenish Prussia, Germany
Died March 9, 1993 (aged 86)
Bloomington, Indiana, United States
Nationality German
Alma mater
University of Hamburg
Known for Zorn's lemma（因佐恩引理而知名）
Scientific career
Fields 
Mathematics
Institutions Indiana University
University of California, Los Angeles
Doctoral advisor Emil Artin
Doctoral students Israel Nathan Herstein
Max August Zorn (German: [tsɔʁn]; June 6, 1906 – March 9, 1993) was a German mathematician. He was an algebraist, group theorist, and numerical analyst. He is best known for Zorn's lemma, a method used in set theory that is applicable to a wide range of mathematical constructs such as vector spaces, ordered sets and the like. Zorn's lemma was first postulated by Kazimierz Kuratowski（波兰数学学派奠基人） in 1922, and then independently by Zorn in 1935. 
Life and career
Zorn was born in Krefeld, Germany. He attended the University of Hamburg. He received his Ph.D. 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-octonions could be represented by a mixed-style of matrices called Zorn's vector-matrix algebra. 
Zorn emigrated to the U.S. and was appointed a Sterling Fellow at Yale University. 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 subsets 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（包括超实数的扩张）. Zorn’s lemma is an alternative expression of the axiom of choice, and thus a subject of interest in axiomatic set theory. （以下省略）