R. Keith Dennis, professor emeritus of mathematics in the College of Arts and Sciences, died Dec. 12 following a prolonged battle with metastatic prostate cancer. He was 80.
A renowned mathematician, Dennis made significant contributions to algebraic K-theory and group theory, publishing 25 papers. His graduate textbook, “Noncommutative Algebra,” co-written with Benson Farb ’89, remains a standard reference in the field.
“He knew how to work examples like no one else, and his special style allowed him to make a number of discoveries many others missed. For instance, he discovered a remarkable mapping in K-theory that was subsequently developed into a very general tool that came to be known as the ‘Dennis Trace,’” said Farb, the Ann Gillian Sheldon Professor of mathematics at the University of Chicago.
In addition to his scholarly research, Dennis was deeply committed to expanding the availability of mathematics books. He served on the Cornell University Faculty Library Board and chaired the Math Library Committee for many years, initiating the library’s efforts to digitize its mathematics collection.
Dennis was instrumental in creating a collections fund, which has grown to be the Mathematics Library’s largest source of supplemental funding for purchasing new mathematics books. Dennis himself was also a generous benefactor of the library.
“The result of all of this is one of the finest collections of mathematics literature in the country, if not the world,” said Kizer Walker, director of collections for the Cornell University Library.
“I worked closely with Keith Dennis ever since I started at the Math Library to enhance our collections of math e-books,” said Henrik Spoon, Physics, Astronomy and Mathematics Librarian and Visiting Scientist in the Cornell Center for Astrophysics and Planetary Science. “He never sought recognition for his work and generosity, and in his final years, Keith took great joy in strategizing how to utilize his contributions to enhance our mathematics collection, gaining and completing collections of math e-books from all main academic publishers.”
In addition to his efforts at Cornell, Dennis worked with the American Mathematical Society (AMS) from 1995 to 2001, serving as the executive editor of Math Reviews (MR) for three years, and then as a consulting editor. During his tenure at MR, Dennis oversaw the shift from print to digital platforms.
“It is hard to overstate the importance of this transition and the subsequent impact the electronic MR has had on mathematics worldwide,” said Tara Holm, professor and chair of mathematics. “Keith’s long and dedicated service to the mathematics community has left an indelible mark.”
Dennis was also a longtime board member for Project Euclid and for the American Institute of Mathematics (AIM). Brian Conrey, AIM director, said Dennis guided the organization on all things to do with library collections and acquisitions.
“He personally donated thousands of books, journals, papers and letters from his own collection to AIM’s library. We will miss his good cheer and positive outlook,” Conrey said.
“Keith’s dedication to the well-being of the department, the Mathematics Library at Cornell and the preservation of mathematical literature worldwide were extraordinary. The best way to think of him is as a steward of all the things about which he cared,” said colleague Ravi Ramakrishna ’88, professor of mathematics and one of Dennis’ former students.
“Keith was a wonderful colleague, always eager to discuss mathematics. He was also a devoted mentor of undergraduates. Over the years, he supervised many undergraduate research projects and his students have gone on to become leaders in group theory and related fields,” said Kenneth Brown, emeritus professor of mathematics.
Dennis’ teaching “changed my mathematical life,” said Farb, noting Dennis was “incredibly kind, patient and encouraging” and “assigned amazing problems. Each one felt like an exciting journey culminating in a treasure waiting at the finish.”
Born March 10, 1944, in Vernon, Texas, Dennis grew up on a rural farm, where he drove tractors, managed heavy irrigation and spent time exploring the woods. He demonstrated his mathematical aptitude early in life and graduated from high school as valedictorian. He received a B.S. in 1966 and a Ph.D. in 1970, both in mathematics from Rice University.
From 1970 to ’71, Dennis worked with Fields medal winner John Milnor at Princeton University’s Institute for Advanced Study, then came to Cornell, where he spent the rest of his career. He was awarded tenure and promotion to associate professor in 1976 and was promoted to full professor in 1981. From 1987 to ’93, Dennis served as chair of mathematics; he retired in 2019.
In 1987, Dennis received a Humboldt Award, which honors leading researchers for their academic achievements; his other honors include being named an inaugural Fellow of the American Mathematical Society in 2013.
Dennis is survived by his sister, Barbara Gayle Kolkhorst; his children, Erick Dennis, Robin Dennis, Lydia Dennis ’07 and Susan Dennis; six grandchildren; and his partner and colleague, Michelle “Mikki” Klinger, undergraduate coordinator of mathematics.
In lieu of flowers, donations may be made to the Fred and Maggie Dennis Fund for the Cornell University Mathematics Library at AMS.
This article also appeared in the Cornell Chronicle.
Linda B. Glaser is news and media relations manager for the College of Arts and Sciences.
