### Faculty Retirements

Four long-serving faculty retired in 2011.

### David Griffeath

(by Timo Seppalainen)

David Griffeath
David Griffeath earned his BA at Dartmouth in 1971 and his PhD
at Cornell in 1976. He began as Assistant Professor in our department
in 1977 and retired as Professor in 2011. His 34-year career at UW-Madison is marked by numerous distinguished contributions in research, education, outreach and service. David enjoyed a 30-year run of National Science Foundation support for his research and along the way won a Sloan, a Romnes Faculty Fellowship, and a Vilas Award. Apart from doing first rate mathematics, David has successfully reached out across the difficult boundaries that separate mathematics from experimental science and mathematicians from experts in education. David's long time collaborator Lawrence Gray from University of Minnesota summed things up in the words ``there is no one quite like him.''

David graduated from Cornell among a group of students of Frank Spitzer who went on to build the foundations of the subject of interacting particle systems within probability theory. This area of mathematics studies systems with large numbers of components that interact randomly. It is inspired by questions from statistical physics, biology and network engineering. David himelf made a number of seminal contributions to the field. Particularly significant ones include a theory of threshold growth dynamics and a description of the clustering patterns of the two-dimensional voter model.

Eventually David went beyond traditional mathematics and became a pioneer of experimental mathematics, a combination of mathematical analysis and computer visualization. In this area his latest, and quite likely the most significant, achievement is the creation of physically realistic mathematical models of snow crystal growth. Formation of snow crystals has puzzled prominent scientific thinkers since the 1500's. Controlled experiments are difficult and realistic microscopic models are not computationally feasible. During the last 5 years David and Janko Gravner (an ex-student of David's and Professor at UC-Davis) have developed a computational model of snow crystal growth that is the first to replicate most observed snow crystal morphology. This work received attention not only in scientific circles but even in popular media, appearing on the front page of the Chicago Tribune and in other outlets such as NPR, Discovery Channel, and The Washington Post.

In the areas of education and outreach David is widely known for popularization of science through his multiple-award winning website ``Primordial Soup Kitchen''. He has also devoted a great deal of energy to the improvement of mathematics education in our secondary schools. He supervised five PhD's in mathematics and co-advised two in other departments.

At various times David served as associate editor for several leading journals: Annals of Probability, Journal of Theoretical Probability, and Statistical Science. David chaired our department during the financially difficult period 2002-2005. Within the broader campus he served on the Physical Sciences Divisional Committee and on the Committee on Disability Access and Accommodation.

### I. Martin Isaacs

(by Don Passman)

I. Martin Isaacs
Marty Isaacs was born and brought up in the Bronx, New York.
He attended the Bronx High School of Science and then the
Polytechnic Institute of Brooklyn. In his senior year at Poly, he
was on the school's winning Putnam team and he placed in the
top tier of individual winners. He was a graduate student at
Harvard University where he studied with Professor Richard Brauer.
His thesis concerned linear groups and a problem of Blichfeldt.
He received his PhD in 1964.

Marty's first academic position was an Instructorship at the University of Chicago. He came to Madison in 1969 as an Associate Professor with tenure and was awarded a Sloan Fellowship in 1971. That same year, he was promoted to Full Professor, at the age of 31. He has been here ever since.

Marty's main research interest is in finite group theory, although he has worked in many other aspects of algebra. He is perhaps the world's leading expert on the character theory of finite groups. Among other things, he is known for the Glauberman-Isaacs character correspondence, his solution of the famous groups of central-type conjecture, and his more recent work refining and better understanding the McKay conjecture. In June 2009, a conference on character theory was held in his honor in Valencia, Spain.

In addition, Marty has always been passionate about teaching and exposition. He is quite possibly the best teacher in our department, and he has numerous teaching awards to prove this. Over the years, he has mentored 25 PhD students, with several more in the works. Marty has written books on character theory, finite group theory, first year graduate algebra, and even one on geometry for college students. For the past 31 years, he has been in charge of the Mathematics Talent Search which offers challenging math problems to middle and high school students throughout the state and the world. It is the Department's leading and most well-known outreach program.

Marty and I have been best friends for 57 years. We were classmates in high school and college, and roommates in graduate school. I know him longer than almost anyone else, even longer than my wife of a mere 48 years. Marty and I both have the same problem-solving philosophy of mathematics, similar mathematical interests, and the same fast-paced approach to research. So we feel comfortable working together. Our PhD advisor once told us that we would not get a degree unless we could put a Hausdorf topology on our results. We were able to do so, but we have remained otherwise inseparable. With retirement, that will change. Marty will be moving to Berkeley to be with his long-time lady friend, and I will remain in Madison with mine. I will surely miss him.

### Don Passman

(by I. Martin Isaacs )

Don Passman
Don Passman is widely recognized as one of the world's
preeminent experts in ring theory, and especially in those parts of
the theory most closely connected to group theory. He has written
two books on group rings including his comprehensive 720 page
opus, which is the standard reference on the subject, and which
was described as being "majestic" and "both encyclopedic and
lucid" in a review in the A.M.S. Bulletin. Don has also written a
graduate text in ring theory, a more technical text titled "Infinite
crossed products" and a long out-of-print book on permutation
groups, which, happily, is about to be reissued by Dover. Of
course, Don is not only a skilled expositor of the topics covered in
his books; he is also the originator of a substantial fraction of this
material. He is the author of well over 150 research papers,
including a major contribution to group-ring theory written when
he was a grad student.

During his more than 40 years at UW, Don has earned and received a number of honors and awards. These include a Romnes Fellowship, a Houses Professorship and distinguished teaching awards from the university and from the M.A.A. Also, Don has been a principal invited speaker at a number of international conferences. In addition to being one of the math department's best teachers and most productive researchers, Don has also contributed by working for many years making up problems for the Talent Search high-school competition and for the algebra qualifying exam. Of course, he has also served our department in numerous other capacities, including his membership in the faculty honors committee.

Don and I first met in our high-school math class in 1954, and our careers have run on nearly parallel paths ever since. We both attended the Polytechnic Institute of Brooklyn as undergraduates, and we both went on to graduate school at Harvard, where we both received PhDs in 1964, working under Richard Brauer. After five or six years of going our separate ways (Don had postdocs at UCLA and Yale, while I spent time at Chicago) we were reunited in Madison, and after more than four decades, we retired simultaneously. Mathematically too, our work began on parallel paths. Four of my first five published papers were coauthored with Passman (although only two of his first five were coauthored with me), and we collaborated on a total of eight papers, the last of which was in 1981. With time, our interests diverged, his toward rings and mine toward groups, but still, if some general algebra question comes up, my first instinct is to ask Don Passman, and more often than not, he manages to provide an answer.

### Stephen Wainger

(by Alex Nagel and Andreas Seeger)

Stephen Wainger

After 44 years of service in the Department of Mathematics, Stephen Wainger retired from the university in December, 2010. Steve did his graduate work at the University of Chicago, receiving an M.S. degree in 1958, and a Ph.D. in mathematics in 1961 under the direction of Elias M. Stein. He joined our department as an Associate Professor in the fall of 1966, was promoted to Professor in 1968, and was named Antoni Zygmund Professor of Mathematics in 1998.

Steve has made deep and important contributions in many areas of mathematical analysis. He has mentored numerous students and postdoctoral visitors, and over his long career, much of his research was done in collaboration with other mathematicians. Richard Askey, Joshua Chover, Alexandru Ionescu, Thomas Kurtz, Alexander Nagel, Peter Ney, Andreas Seeger and Daniel Shea were among his colleagues here in Madison who had the pleasure working with Steve. His Ph.D. work dealt with asymptotics of special trigonometric series in several variables. After his graduate work he became interested in special function expansions, probability, and complex analysis. For his entire career, he has been a leading figure in harmonic analysis; he is perhaps best known for his pioneering work on Hilbert transforms and maximal functions along curves and surfaces. In recent years, he has turned to problems in one of his best-loved areas, analytic number theory. In particular he has studied discrete analogues of singular integral operators and maximal functions, and as a result has made important contributions to ergodic theory.

Although the list of Steve's mathematical interests and accomplishments is long and impressive, its recitation does not fully capture Steve's importance to our department and to the mathematical profession. No matter where your mathematical travels take you, people will ask about Steve, and send their greetings. To know Steve is to know an individual with an almost unbelievable dedication to teaching, talking, learning, supervising, encouraging, and doing mathematics. And this is done with infectious enthusiasm, charm, and humor. Most of our colleagues, though special to us, are perhaps not all that dissimilar from other people we know. However, there is only one Steve Wainger.