**Juan Jorge Schäffer** was born in Austria, became a citizen of Uruguay where he had most of his schooling and undergraduate studies, and worked at Carnegie Mellon University in Pittsburgh, USA from 1968. His outstanding research papers on functional analysis and ordinary differential equations made important contributions to the development of mathematics in Uruguay.

- The first thing we must make clear is that Juan Jorge Schäffer was the name that he made official when he became a citizen of Uruguay but at birth he was given the name Hans Jörg Schäffer.
- We shall use Juan Jorge throughout this biography.
- Daniel Schäffer, one of four siblings, was born in Temesvár, Hungary, which is now Timișoara, Romania.
- Daniel Schäffer had good contacts abroad, particularly in Zurich, Switzerland.
- Juan Jorge learnt French from his parents, who insisted that he learn that language.
- She died in 1937 and later that year Juan Jorge went with his parents on a skiing holiday to Switzerland.
- Daniel and Margarethe decided to return to their home to see what could be salvaged and left Juan Jorge in Switzerland with their Swiss friends.
- Juan Jorge already spoke French so attending school in Paris was not a problem.
- Schäffer particularly remembered a notable event which happened on 9 September 1945 when Uruguay changed from driving on the left to driving on the right.
- Schäffer had a great aptitude for languages speaking German and French fluently before arriving in Uruguay.
- Given this unpleasant situation, Schäffer's parents moved him to a British school.
- Two separate British schools had been founded in Montevideo in 1908, one for boys and one for girls, but by the time Schäffer studied there the two school had merged.
- The education at this school was good and Schäffer quickly added English to his growing language skills.
- After the award of the baccalaureate, Schäffer entered the University of Montevideo to study engineering.
- Schäffer, who studied mathematics as part of the engineering course, attended the same lectures by Halmos as his friend Lumer.
- Schäffer's stuff would be a snow job - each crystal was impeccably clean but the mass could be incomprehensible in its impressive totality.
- Halmos, Lumer and Schäffer wrote the joint paper Square roots of operators which they submitted to the American Mathematical Society on 4 April 1952.
- Schäffer graduated from the University of Montevideo with a degree in industrial engineering and was awarded a fellowship which allowed him to choose where he studied for a doctorate.
- Schäffer didn't, however, adopt Nevanlinna's proposal for his thesis topic.
- Bartel van der Waerden had been on the staff at the University of Zurich from 1951 and he gave Schäffer some advice concerning his thesis.
- In 1957 Schäffer was awarded the degree of Doctor of Philosophy from the University of Zurich for his mathematics thesis Analytische Parameterabhängigkeit der fastperiodischen Lösungen von nichtlinearen Differenzialgleichungen Ⓣ(Analytical parameter dependence of the almost periodic solutions of nonlinear differential equations.).
- Returning to Uruguay, Schäffer was appointed to teach engineering and mathematics at University of Uruguay in Montevideo.
- José Luis Massera had taught Schäffer when he was an undergraduate in Montevideo and they became colleagues when Schäffer joined the staff at the University of Uruguay.
- While Schäffer was still an undergraduate they published the joint papers Minimum figures covering points of a lattice (Spanish) (1951) and On the level curves of a convex surface (Spanish) (1953).
- We note that Mathematical Reviews lists 50 papers published by Schäffer before this 1966 book.
- He had an invitation to Carnegie Mellon University in Pittsburgh so, in 1968, they moved to Pittsburgh where Schäffer worked for the rest of his career.
- In addition to the books he wrote with José Luis Massera, Schäffer wrote three other books: Geometry of spheres in normed spaces (1976); Basic Language of Mathematics (2014); and Linear Algebra (2014).
- Schäffer was interested in the history of mathematics and developed a course on the topic.
- Schäffer's wife, Inge Doris Schäffer, died on 15 September 2008 and she was buried in Homewood Cemetery, Pittsburgh.
- Her name appears on her tombstone as "Inés Schäffer".
- Schäffer died in 2017 and was also buried in Homewood Cemetery.

Born 10 March 1930, Vienna, Austria. Died 12 February 2017, Pittsburgh, Pennsylvania, USA.

View full biography at [MacTutor](https://mathshistory.st-andrews.ac.uk/Biographies/Schaffer/

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive