In Memoriam

In Memory

Miriam Cohen

The mathematical community mourns the loss of our beloved colleague and friend, Miriam (Mia) Cohen (1941--2023), emeritus professor at Ben-Gurion University.

Mia began her mathematical career studying non-commutative and graded rings and became Israel’s
pioneer in the study of Hopf algebras. When quantum groups emerged, she was among the leading figures
advancing their understanding from an algebraic perspective. Her work helped reveal deep connections
between these algebraic structures and knot theory, C*-algebras, and quantum field theory.

In the 1970s, Mia helped unify non-commutative Galois theory and group-graded algebras by showing
they could both be viewed as H-module algebras over suitable Hopf algebras . This insight, together with
her work on smash and cross products, inspired extensive research and lasting developments in the field.
Following Drinfeld’s introduction of quantum groups in the 1980s, Mia advanced their algebraic
foundations. She generalized Schur’s double centralizer theorem to triangular Hopf algebras and
introduced quantum-commutative algebras within Yetter–Drinfeld categories, developing quantum
versions of Fourier transforms and Verlinde-type formulas. In her later work, Mia extended the notion of
conjugacy classes from groups to Hopf algebras, providing new structural insight into semisimple Hopf
algebras, analogous to that of finite groups.

Mia will be remembered for her pioneering vision, intellectual rigor, and generosity of spirit. Her legacy
endures in the strength of the Israeli algebraic community she helped shape. Her wisdom, warmth, and
dedication to students and colleagues left a profound mark on all who had the privilege to know her.

Moshe Roitman

Moshe Roitman was born in 1944 in Constanța, Romania, and immigrated to Israel in 1961. He studied at the Hebrew University in Jerusalem, graduating in 1968 with a B.Sc. in mathematics and physics, then completing an M.Sc. thesis under S. A. Amitsur in1969, and a Ph.D. dissertation “On Serre’s problem on projective modules” under H. Furstenberg in 1977.

He joined the Department of Mathematics at the University of Haifa in 1980, was promoted to senior lecturer in 1985, associate professor in 1990, and full professor in 2000. He held visiting positions at Queen’s University in Kingston, Ontario in 1985-86 and at the University of North Carolina in 1990-91 and served as department chair in 2001-03. He passed away on September 3, 2025.

Moshe wrote more than 60 papers in various areas of algebra and number theory, the last appearing in 2023. In his early research, finitely generated projective modules over polynomial rings (and extensions) were focal, with important and well-acknowledged contributions towards the solution of Serre’s famous conjecture, starting with his thesis.

Another significant strand in his research was the examination of well known theorems and notions in Noetherian commutative ring theory and their possible counterparts in the non-Noetherian world. The list of topics includes Mori rings, stable rings, Bezout domains, Nagata’s class group theorem, and many more.

Moshe wrote a few papers in analysis, mostly around the question of when a linear functional is multiplicative.

There are also sporadic papers on elementary number theory, finite groups, and conjugacy classes.

Joseph B. Muskat

The IMU regrets to announce that Joseph Baruch Muskat, professor emeritus at Bar-Ilan University, has passed away. He worked in number theory, specializing in algorithmic methods in number theory, and was a leading figure in the mathematics and computer science department at Bar-Ilan from 1970 and well past his retirement in 2003 and last course in 2011, warmly welcoming new immigrant faculty and first-year students alike.