It’s common for friends and family to come together to celebrate milestone birthdays. For the Stewart School’s George Nemhauser, A. Russell Chandler III Chair and Institute Professor, and Arkadi Nemirovski, John Hunter Chair and professor, more than 200 people traveled from across the globe to convene in Atlanta for a birthday celebration unlike all others: NemFest, a two-day optimization conference held May 11-12, 2017, at Georgia Tech’s Historic Academy of Medicine. Leading experts in the field, colleagues, and students gathered for Nemirovski’s 70th birthday and Nemhauser’s 80th birthday, celebrating what the organizers called a collective “150 years of contributions to optimization.”

It is not an overstatement to say that the two colleagues and friends have made an extraordinary impact on their specialties within optimization, and as a result have advanced not only the field, but also ISyE and Georgia Tech.

Unexpected Paths

Neither Nemhauser, a native of the Bronx, New York, nor Nemirovski, a native of Moscow, Russia, ever expected that they would land in Atlanta or at Georgia Tech.

Nemhauser said, “I never thought I would have achieved what I’ve achieved. I was a pretty ordinary kid, and being a professor was not on my mind early on.” After earning his undergraduate degree in chemical engineering from City College in New York, he began

his graduate studies in chemical engineering at Northwestern University at the urging of his parents because, he said, “I needed to do something practical.” He didn’t begin to consider operations research until he encountered Jack Mitten, a professor who had an enormous influence on him. “I had no idea of what professors were like or what they did, and he took me into his home, and I got to know his family,” said Nemhauser.

Nemhauser entered the emerging field of operations research and went on to join the faculty of Johns Hopkins University in 1961. He was appointed professor of operations research and industrial engineering at Cornell University in 1970 and served as school director for a number of years.

Nemhauser came to ISyE in 1985 as the A. Russell Chandler III Professor and was appointed Institute Professor in 1991. He also has held visiting faculty positions at the University of Leeds, United Kingdom; the Catholic University of Louvain, Belgium; and the University of Melbourne, Australia. At Louvain, he worked at the Center for Operations Research and Econometrics, serving as research director for two years.

Similar to Nemhauser, Nemirovski did not anticipate a career in academia. When he was 15 years old, Nemirovski’s parents transferred him to a high school that focused on mathematics.

While his interest in mathematics was firmly established, he said, “I never thought about academia before my move to Israel.”

After earning his Ph.D. in mathematics from Moscow State University, Nemirovski began his career as a research associate for the Institute for Automatic Equipment and the Central Economic and Mathematical Institute of the USSR/Russian Academy of Sciences, both in Moscow. In 1993, he left Russia to take a position as a professor at the Israel Institute of Technology in Haifa, where he served on the faculty of the industrial engineering and management department.

Twelve years later he relocated once again, this time to Atlanta, where he joined ISyE as the John Hunter Jr. Chair and professor in 2005.

Nemirovski said, “Two years prior to my departure to Israel, I was absolutely sure I would never leave Russia. When I came to Tech for a sabbatical in 2003, it was two years prior to accepting the position here. I was absolutely sure I would never live here. So, the conclusion is you should never say never.”

Describing his decision to join the Stewart School, Nemirovski said, “One of the reasons I was attracted to ISyE is that the School has come to be highly regarded as a magnet for talented researchers, largely due to the direct or second-order influence of George Nemhauser. ISyE’s environment and enthusiasm for fundamental research have clearly made it a go-to destination for scholarly work.”

Unparalleled Careers, Extraordinary Impact

It’s been said that to make decisions optimally is one of the basic desires of humankind. Optimization, the mathematically rigorous methodology for seeking a best action among a multitude of alternatives, is a key design and operational tool in many critical applications including energy, finance, health, transportation, and manufacturing systems; social networks; and supply chains.

Although Nemhauser and Nemirovski focus on different areas of optimization, they are similar in that the breadth and depth of their contributions to the field are unparalleled. Both are pioneers in their areas of research, and both have fundamentally shaped the field as a result of their work — and the Stewart School. ISyE boasts the largest single-program concentration of faculty with optimization as their primary area of research expertise in the world — an achievement directly related to the influence of Nemhauser and Nemirovski.

Describing Nemhauser and Nemirovski as “two towers in the field of optimization,” ISyE Assistant Professor Andy Sun said, “George and Arkadi are amazing figures. Any one of their achievements could be a lifetime achievement for somebody, but they have made all of these very fundamental  contributions.”

Nemhauser works in integer programming, which is the name for optimization models and algorithms in which some variables are required to have integer values. Integer programming has a big impact on solving important problems in industry. Most Fortune 500 companies use integer programming in some aspect of their business. Current software is capable of solving models with thousands, and sometimes millions, of variables and constraints.

With more than 200 publications and over 25,000 citations to his name, Nemhauser co-authored what is considered the textbook on integer and combinatorial optimization since its publication more than 25 years ago.

In 1986, he was the first sitting professor at Georgia Tech to be elected to the National Academy of Engineering (NAE), and for a time, Nemhauser was the only NAE member not only at Georgia Tech but also in the state of Georgia. He has won every major award in his field of optimization, including the field’s first-ever Khachiyan Prize for lifetime achievement in 2010. More recently, in 2015 he received the Class of 1934 Distinguished Professor Award, the highest recognition accorded to a faculty member at Georgia Tech.

Nemhauser’s impact on industry is equally extraordinary. From scheduling in the airline industry to the sports industry, his optimization techniques have been widely adopted. He has made contributions in applications as diverse as political districting, facility location, portfolio management, supply chain optimization, maritime inventory routing, military resource allocation, semiconductor manufacturing, and float glass manufacturing, among other areas. Nemhauser is also one of the developers of MINTO, a software system used in integer programming research.

Since he joined the faculty at Georgia Tech more than three decades ago, Nemhauser has been critical to ISyE’s rise in national undergraduate and graduate rankings and its ability to remain there for 23 and 27 continuous years, respectively.

Similarly, Nemirovski has enjoyed a remarkable career. His research interests focus on optimization theory and algorithms, with emphasis on investigating complexity and developing efficient algorithms for nonlinear convex programs, optimization under uncertainty, applications of convex optimization in engineering, and nonparametric statistics.

Throughout the course of his long career, Nemirovski has made significant contributions in several areas. At the age of 27, while on vacation, he invented the ellipsoid method, which is one of the most fundamental developments in optimization.

Later, with Yurii Nesterov, Nemirovski developed the interior point method—a second game- changer and breakthrough in the field. This is an algorithm that has been used for solving convex optimization problems and is used as a tool to classify problems.

Yet another contribution of his centers on the development, with Ronny Ben-Tal, of the field of robust optimization, which is a modeling contribution. Here, they created a framework that is able to handle uncertainty in problem data.

According to Anderson-Interface Chair and Professor at ISyE Shabbir Ahmed, the significance of some of the general optimization theory Nemirovski developed was not recognized early on. Ahmed said, “But with the growth of analytics, machine learning, and data, more and more of these convex optimization problems are occurring, and there is a need for solving optimization problems with very large data sets.” He described Nemirovski as ahead of his time, anticipating the solution to a problem that was yet to exist.

In recognition of his seminal and profound contributions, Nemirovski has been awarded the top prizes in the field: the 1982 Fulkerson Prize from the Mathematical Programming Society and the American Mathematical Society (joint with Leonid Khachiyan and David Yudin); the Dantzig Prize from the Mathematical Programming Society and the Society for Industrial and Applied Mathematics in 1991 (joint with Martin Grötschel); and the 2003 John von Neumann Theory Prize by the Institute for Operations Research and the Management Sciences (along with Michael Todd).

Nemirovski was elected to the NAE in February 2017, the first year he was eligible for induction. In announcing his election to the prestigious organization, the NAE commended Nemirovski for his work in “developing efficient algorithms for large-scale convex optimization problems.”

Describing Nemirovski’s many contributions, Nemhauser said, “His influence in terms of the quality of work is just amazing. In the area of nonlinear optimization, he is the world’s No. 1 leading researcher and has been for quite a while. He is just an enormous influence on the field.”

While Nemhauser and Nemirovski are renowned for their contributions to the field, they are also admired for their humbleness, generosity, and support of colleagues and students at ISyE.

Ahmed said, “This is a unique feature of ISyE— people like George and Arkadi set the tone for the faculty. People of their stature are superstars, but they would never give you that impression and will always have time for you. They are willing to help whomever seeks their help.”

Both Nemhauser and Nemirovski have taught undergraduate and graduate courses, and Nemhauser played a critical role in revamping how optimization is taught at the undergraduate level at ISyE.

Nemhauser has worked with approximately 70 Ph.D. students, more than any other professor in the field of operations research. Today, his former students are on the faculty of almost every top operations research department in the country, including MIT, Berkeley, Cornell, and Georgia Tech.

ISyE Professor Natashia Boland is a former postdoctoral student of Nemhauser, and she credits him with changing the course of her career. Boland said that from him, she has learned that “it’s important to motivate the theory from your applications”— meaning that inspiration comes from working on real problems with industry.