Compositio Mathematica mourns the untimely death of Bas Edixhoven on 16 January 2022.

Bas Edixhoven was born on 12 March 1962 and grew up in the Netherlands. He studied Mathematics in Utrecht and obtained his PhD in 1989 under the supervision of Frans Oort. After two years in Berkeley and one in Utrecht, he obtained a professorship in Rennes. In 2002 he returned to the Netherlands, taking up a chair in Leiden.

Bas acted as managing editor for Compositio Mathematica from 2003 until 2012. After this he became a board member of the Foundation Compositio Mathematica. In his role of secretary of the Board he was responsible for many practical matters, which he handled with dedication. He was strongly committed both to the scientific quality of the journal and to the ideals of the foundation.

He was an excellent researcher working in arithmetic algebraic geometry. He made important contributions, notably to the study of modular curves and modular forms, Serre's conjecture on modularity of Galois representations, the theory of Néron models, and the André–Oort conjecture. He was also much interested in computational aspects, as witnessed for instance by the book about the computation of modular forms and Galois representations that he co-authored.

Bas was a mathematician who found great joy in discussing problems or new mathematical ideas. He was very generous in sharing his knowledge with colleagues and students. During his career he supervised around 25 PhD students. He had a warm and cheerful demeanour; many of us will remember his characteristic slightly suppressed smile, usually followed by an interesting argument or insightful comment. Bas was allergic to appeals to authority, and always tried to engage critically on the basis of genuine arguments.

Bas paid attention to people less privileged than he. In his views on how to make the world a better place he set an example by being a very practical person, devoting much time and energy to ecological projects.

Bas passed away after a short illness. He spent his last days at home, surrounded by his family.

He will be dearly missed.

The managing editors since 2002:

• Gerard van der Geer

• Jochen Heinloth

• David Holmes

• Bruno Klingler

• Ben Moonen

• Eric Opdam

• Lenny Taelman

• Burt Totaro

• Eric Vasserot

On behalf of the Foundation Compositio Mathematica:

• Gerard van der Geer, president