08/25/2025
A message from Trondheim:
Dear colleagues and friends,
It is with great sadness we announce that Idun Reiten passed away on August 19th, after a long illness.
Idun was born January 1, 1942. She received her PhD at the University of Illinois at Urbana-Champaign in 1971 as a student of Robert Fossum. She was appointed as an associate professor at AVH (now NTNU) in Trondheim in 1974, and promoted to a professorship in 1982.
Her work with Maurice Auslander from the 1970s on almost split sequences and irreducible morphisms—and what is now called Auslander–Reiten theory—has made a huge impact on the field of representation theory and beyond. Together with Auslander and Sverre Smalø, she authored an excellent textbook on the subject, for many years a very influential source. Later milestones include her work on tilting in hereditary abelian categories and quasi-tilted algebras; on cluster categories and cluster-tilting, and most recently her very influential work on tau-tilting theory with coauthors. In addition, some of her work has dealt with commutative ring theory and the theory of orders. Throughout her whole career, homological methods have been central in much of her work.
Over the years, Idun received numerous awards and recognitions; let us mention a few. She was an invited speaker at the ICM in 1998 in Berlin, and again in 2010 in Hyderabad, this time delivering the Emmy Noether Lecture. In 2005 she received a Humboldt Research Award, and in 2007 she was elected a foreign member of the Royal Swedish Academy of Sciences. She was also a fellow of the American Mathematical Society, a member of Academia Europaea, and an honorary doctor at the University of Bielefeld. Among her many national recognitions, we mention one: in 2014 the King of Norway appointed Idun as a Commander of the Order of St. Olav, for her contributions to mathematics.
We remember Idun as an outstanding mathematician and a great teacher and mentor. Her ideas were original and creative. She gave wonderfully well-prepared and crystal-clear lectures and talks, to students in Trondheim as well as at international conferences and seminars.
On a personal note, we also remember Idun for her laughter, her friendliness, and her generosity. Despite all the prizes and honour, she always remained down-to-earth and humble. She kept her door open to colleagues and students, and she was always very welcoming and helpful to young mathematicians. Idun was our teacher and friend. She will be sadly missed.
The algebra group at NTNU in Trondheim
Idun Reiten (1 January 1942 – 19 August 2025) was a Norwegian professor of mathematics. She is considered to be one of Norway's greatest mathematicians today.[3] With national and international honors and recognition, she had supervised 11 students and had 28 academic descendants as of March 2024....
