Jan-Erik Roos

{{Short description|Swedish mathematician (1935–2017)}}

Jan-Erik Ingvar Roos (16 October 1935 – 15 December 2017){{cite journal|journal=Bulletinen|date=15 February 2018|pages=3–6| url=http://www.swe-math-soc.se/pdf/SMSbull1802.pdf|first=Ulf |last=Persson|title=Jan-Erik Roos 16/10/1935 – 15/12/2017|language=sv|access-date=3 June 2020}} was a Swedish mathematician whose research interests were in abelian category theory, homological algebra, and related areas.

He was born in Halmstad, in the province of Halland on the Swedish west coast. Roos enrolled at Lund University in 1954, and started studying mathematics with Lars Gårding in 1957. Under Gårding's direction he wrote a thesis on ordinary differential equation, and graduated in 1958 with a licentiate degree.{{MathGenealogy|id=20546}} Later that year he went to Paris on a doctoral scholarship; there, he gravitated towards the mathematical environment at the Institut Henri Poincaré, and the various seminars held there. After a while, he started attending Alexander Grothendieck's seminar at the Institut des hautes études scientifiques in Bures-sur-Yvette, where he became interested in abstract algebra and algebraic geometry.{{cite journal|journal=Bulletinen|date=15 February 2018|pages=6–10| url=http://www.swe-math-soc.se/pdf/SMSbull1802.pdf|first=Olav Arnfinn| last=Laudal|author-link=Arnfinn Laudal|title=Jan Erik Roos in Paris|language=sv|access-date=3 June 2020}} In 1967 he was invited by Saunders Mac Lane to visit the University of Chicago for three months; Mac Lane was impressed by Roos and later wrote a very positive letter of recommendation for him.{{cite journal|journal=Bulletinen|date=15 February 2018|pages=10–13| url=http://www.swe-math-soc.se/pdf/SMSbull1802.pdf|first=Gert | last=Almkvistl|title=My friend Jan-Erik Roos|language=sv|access-date=4 June 2020}}

Upon his return to Sweden, Roos was appointed Professor of Mathematics at Stockholm University in 1970, and started building a strong algebra school. He was elected to the Royal Swedish Academy of Sciences in 1980 and was its President from 1980 to 1982.{{cite journal|url=https://www.ems-ph.org/journals/newsletter/pdf/2012-06-84.pdf|journal=European Mathematical Society Newsletter| volume=84| pages=16–18|date=June 2012|title=Torsten Ekedahl|first=Jan-Erik|last=Roos|access-date=4 June 2020}} While serving on the Academy, he was on the committees deciding the Rolf Schock Prizes in Mathematics{{cite web|title=Rolf Schock – uniting philosophy, mathematics, music and art|url=https://news.cision.com/kungl--vetenskapsakademien/r/rolf-schock---uniting-philosophy--mathematics--music-and-art,c9535496|website=news.cision.com|date=13 February 2014|access-date=3 June 2020}} and the Crafoord Prize in Astronomy and Mathematics.{{cite web|title=The Crafoord Prize in Mathematics and Astronomy 2008| url=https://crafoordprize.se/press_release/the-crafoord-prize-in-mathematics-and-astronomy-2008|website=crafoordprize.se|date=17 January 2008|access-date=3 June 2020}}

Roos made important contributions to homological algebra, and did extensive computer-assisted studies of Hilbert–Poincaré series and their rationality.{{Cite journal|last=Avramov|first=Luchezar L.|author-link=Luchezar L. Avramov|date=2002|title=The work of Jan-Erik Roos on the cohomology of commutative rings|url=https://projecteuclid.org/euclid.hha/1139852454|journal=Homology, Homotopy and Applications|language=EN|volume=4|issue=2|pages=1–16|issn=1532-0073|mr=1918181|zbl=1003.01010|doi=10.4310/HHA.2002.v4.n2.a1|doi-access=free}} A special issue of the journal Homology, Homotopy and Applications ("The Roos Festschrift volume") was published in 2002, on the occasion of his 65th birthday.{{Cite journal|editor1-first=Larry|editor1-last=Lambe|editor2-first=Clas|editor2-last=Löfwall|title=The Roos Festschrift volumes 1 and 2|

url=https://projecteuclid.org/euclid.hha/1139852453|journal=Homology, Homotopy and Applications|date=January 2002 |volume=4|issue=2|pages=ii–vi, 1–225 and 227–437|mr=1918180}} and {{MR|1918521}}

He died on 15 December 2017 at his home in Uppsala{{cite journal|url=https://www.lms.ac.uk/sites/lms.ac.uk/files/files/NLMS_477_reduced_0.pdf|title=Jan-Erik Roos: 1935–2017|journal=London Mathematical Society Newsletter |volume=477 |year=2018|page= 45|mr=3837430}} and is buried at the Uppsala old cemetery.