**Dan Mostow** was an outstanding mathematician winning the Leroy Steele Prize in 1993 and the Wolf Prize in Mathematics in 2013 for his fundamental and pioneering contribution to geometry and Lie group theory. He also played a major role in supporting mathematics as president of the American Mathematical Society and in many other leading roles.

- Jack's occupation is "news worker", seeking work, while Dan has no occupation and is a student.
- In 1936 Dan had entered the Boston Public Latin School at the same time as Daniel Gorenstein; the two became lifelong friends.
- Dan earned money by working as a newsboy and, in addition, as a general helper in a catering hall.
- Mostow was awarded the 'Latin School Class of 1898', the prize given to the top pupil.
- As a consequence, Mostow began teaching courses which were part of the training for officers, namely a spherical trigonometry course and a plane trigonometry course.
- Before Mostow had submitted his doctoral thesis, in June 1947, he was offered a 2-year stay at the Institute for Advanced Study in Princeton and, to run in parallel, a one year position as Instructor in Mathematics at Princeton University.
- Mostow's thesis was The Extensibility of Local Lie Groups of Transformations and Groups on Surfaces and he was awarded a Ph.D. for this in 1948.
- This was not Mostow's first publication since his paper A new proof of E Cartan's theorem on the topology of semi-simple groups was published in 1949.
- Let us give here a summary of Mostow's career.
- He had been encouraged to accept this position by Atle Selberg who was on the faculty there, but Selberg had left Syracuse by the time Mostow took up his post in 1950.
- At Syracuse, Mostow became a colleague of Lipman Bers and the two became lifelong friends.
- There were tensions at Syracuse, however, between researchers and teaching-only members of the Department so when Mostow was offered an Assistant Professorship at Johns Hopkins University in 1952 he was pleased to accept.
- Mostow retired from his Chair at Yale in 1998 and, in the following year, was made Professor Emeritus.
- Evelyn Mostow died on 16 September 2005.
- Mostow received many honours for his outstanding contributions.
- Mostow's rigidity methods and techniques opened a floodgate of investigations and results in many related areas of mathematics.
- Mostow's emphasis on the "action at infinity" has been developed by many mathematicians in a variety of directions.
- Mostow's contribution to mathematics is not limited to strong rigidity theorems.
- Mostow's work on examples of nonarithmetic lattices in two and three dimensional complex hyperbolic spaces (partially in collaboration with P Deligne) is brilliant and lead to many important developments in mathematics.
- In Mostow's work one finds a stunning display of a variety of mathematical disciplines.

Born 4 July 1923, Boston, Massachusetts, U.S.A.. Died 4 April 2017, Hamden, New Haven, Connecticut, USA.

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Group Theory, Origin Usa, Prize Wolf

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive