August 28, 2023

Melvin Gordon Rothenberg, a professor emeritus of mathematics who spent more than four decades making groundbreaking mathematical discoveries at the University of Chicago as well as teaching hundreds of students and contributing to social justice causes, died August 1, 2023. He was 89.

Rothenberg made multiple contributions in the mathematical fields of algebraic and geometric topology that form the foundation of work still ongoing today.

He was also beloved by students and young faculty and “will be remembered by those who knew him for his human qualities even more than by his theorems,” says Shmuel Weinberger, the Andrew MacLeish Distinguished Service Professor of Mathematics at UChicago, who was recruited by Rothenberg 40 years ago.

## Math and humanity

Born in Boston in 1934, Rothenberg was raised in Cleveland, where he met Marcia Cherko, who would become his wife of over 70 years, while working on their high school newspaper. He studied philosophy and mathematics at the University of Michigan, Ann Arbor and was recruited by the University of California, Berkeley for his master's and doctorate degrees. There he studied under P. Emery Thomas, wrote his dissertation “On the Milnor Construction of Universal Bundles,” and earned his PhD in 1962. He had joined the University of Chicago as a math instructor the year prior.

Rothenberg’s field was topology: the mathematical study of an object’s properties that are preserved as it changes shape, such as through twisting or stretching. For example, a circle is topologically the same as an ellipse. His early work focused on algebraic topology, related to the unstable version of the J-homomorphism. With Norman Steenrod, he found a spectral sequence for the cohomology of the classifying space of an H-space.

He then moved to work in geometric topology, where his contributions were fundamental and groundbreaking. His two largest collaborations were with Dick Lashof and with Ib Madsen. With Lashof, he made important early contributions to smoothing and triangulation theory and equivariant triangulation theory. His work with Madsen showed that it was possible to understand odd order group actions by surgery theoretic means.

## ‘Incredibly warm’

In addition to his mathematics work, Rothenberg was a beloved colleague and teacher.

“When I first arrived at UChicago as a Dickson instructor in 1994, Mel made the transition much more pleasant for me,” says mathematics professor Benson Farb. “He was incredibly warm, kind, and generous with his time.” He cites one of Rothenberg’s students insisting on studying gauge theory, which the professor didn't know. “Mel's response was to dive in, learn it quickly, and advise the student (now a very successful mathematician) on this topic.”

Rothenberg is fondly remembered as the paradigm of an absent-minded professor. “His foibles (such as his inability to spell names correctly or to keep his shirt tucked in) made him accessible despite his sharpness,” says Weinberger.

Rothenberg was also committed to social justice and political activism. For decades, he and Marcia attended protests against political repression and the Vietnam War and in support of civil rights, women’s liberation, and health care for all. Rothenberg was a committed Marxist and scholar of Marx and political economy. He wrote for socialist journals, including *Against the Current*, and could be found advocating for change through peaceful means on public access television, recalls Farb. “Mel was the kind of person that made and makes UChicago ... well, UChicago.”

Rothenberg’s wife Marcia June Rothenberg (née Cherko) preceded him in death by two and a half months. He is survived by children Julia Helise Rothenberg and her husband, Geoffrey Berliner; Aaron Rothenberg; and Louise Michelle Rothenberg; and a grandchild, Theo Rothenberg Berliner.

*This article contains material authored by Prof. Shmuel Weinberger. **Read more about Mel Rothenberg’s work.*