Center will expand the Department of Mathematics’ research in mathematics and statistics.

The University of Maryland announces today a $4.75 million gift to its Department of Mathematics to expand research in pure and applied mathematics and statistics. 

Mathematics Professor Emeritus Michael Brin and his wife Eugenia and the Sergey Brin Family Foundation are establishing the Brin Mathematics Research Center, which will expand the university’s mathematics and statistics research and education programs and support visiting scholars, workshops and symposia, and summer programs.

“The impact and generosity of the Brin family here at the University of Maryland is extraordinary,” said Amitabh Varshney, dean of the College of Computer, Mathematical, and Natural Sciences. “We are honored that the Brin family’s latest gift will support pure mathematics and statistics research and its applications to nearly every sector of our economy.”

 The center will provide a platform for UMD to expand and showcase its mathematics and statistics research excellence nationally and internationally. It will also foster interactions between mathematicians at UMD and around the world.

Housed in the Computer Science Instructional Center, the center will organize its activities around annual themes. Each year will be dedicated to several different research areas. The center will invite visiting scholars and host scientific meetings on these themes. 

 “The University of Maryland was a welcoming home for our family for many years. We hope that the new center will significantly advance mathematics research at Maryland,” said Michael Brin, who retired from UMD in 2011 after 31 years on its faculty.

Michael and Eugenia, a retired NASA scientist, parents to Google co-founder Sergey (B.S. ’93, mathematics and computer science) and Samuel (B.S. ’09, computer science), have made several significant gifts over the years to support the university’s Department of Mathematics; Department of Computer Science; Russian program; and School of Theatre, Dance, and Performance Studies.

“This gift is truly transformational for our department,” said Doron Levy, chair of the Department of Mathematics and inaugural director of the Brin Mathematics Research Center. “With exciting faculty hires, an expanded postdoctoral program, new research opportunities and many educational initiatives, our department aims to be one of the top mathematics departments in the world. The Brin Mathematics Research Center is key to achieving our goals. The level of support it will provide to our research activities is unprecedented within the mathematical community. On behalf of my colleagues, I would like to thank the Brin family for their outstanding gift.”

 The department currently ranks 9th in the nation among public institutions according to U.S. News & World Report and has over 100 tenured/tenure-track and professional-track faculty members, nearly 800 undergraduate majors and 200 graduate students, and teaches about 10,000 students a semester.

The Brin family’s generous gift supports Fearless Ideas: The Campaign for Maryland, UMD’s $1.5 billion fundraising campaign focused on elevating and expanding the university’s mission of service, enhancing academic distinction and bolstering UMD’s leading-edge research enterprise.

Celebrating 80 years with Distinguished University Professor Emeritus Jim Yorke, the “Father of Chaos.”

James “Jim” Yorke has held many titles during his career as a mathematician at the University of Maryland—from Ph.D. student to Distinguished University Professor—but he prefers just one: coach.

“A coach is supposed to help you excel, but I don't know what a professor is supposed to do, profess?” said Yorke (Ph.D. ’66, mathematics). “If I want facts, I can get them from books.” 

Yorke wasn’t being snarky. He was posing a challenge to see things differently, more deeply—the way he always has throughout his nearly 60-year career. 

“I still think of him as Coach,” said Laura Tedeschini-Lalli (Ph.D. ’86, applied mathematics), a professor of mathematics at Roma Tre University in Rome, Italy, who was one of Yorke’s students. “He used to tell us, ‘A teacher can teach you part of what he knows and that’s about it, but a coach helps you excel at what you do well.’ And really, he goes beyond teaching about math. He gets to know people, and through his humanity he helps people excel as mathematicians, but also as better human beings.” 

That sentiment was echoed over and over as more than 100 of Yorke’s colleagues, friends and former students celebrated his 80th birthday on September 18, 2021. The celebration, held virtually on Zoom, included six scientific talks and two hours of toasts.

During his toast, S. James Gates Jr.—a College Park Professor of Physics, National Medal of Science awardee and the current president of the American Physical Society—called Yorke the closest thing to a Renaissance man he had ever met and said he appreciated “opportunities to follow such a broadly intellectual and forceful personality.”

DJ Patil (M.A. ’99, Ph.D. ’01, applied mathematics), one of Yorke’s graduate students who went on to serve as the first U.S. chief data scientist, said Yorke helped set the tenor for the open, creative culture that taught him what a collaborative environment should be.

Equally impressive was the number of younger scientists who said Yorke made them feel valued and at home, including high school student Ishan Saha, who reached out to Yorke last year with questions about chaos. Saha chimed in to raise a water-filled glass to the famed mathematician who generously met with him weekly to talk about math and science. 

Wayne Hayes, a former postdoctoral associate who is now an associate professor in the Donald Bren School of Information and Computer Sciences at UC Irvine, joined the celebration while on a motorcycle trip. He tipped his helmet to Yorke and reminisced about his first few days at UMD when Yorke lent him cash to pay rent because he was unable to access his Canadian bank account. 

Yorke’s humanity and generosity made an impact on students and colleagues far and wide, and although he has published more than 300 papers, his priority has always been connecting with the people around him.

“I like to work with people,” he said. “I haven’t had a single-author paper since 1970-something. You bring in more people and you end up with better papers.” 

Nor has he stayed in his lane as a mathematician. Over his career, Yorke’s co-authors have hailed from fields as diverse as epidemiology, meteorology, ecology and artificial intelligence. The six invited speakers at his celebration presented recent research they collaborated on with Yorke that spanned topics ranging from laying the groundwork for ensemble weather prediction models to simplifying methods for reconstructing the largest genome ever assembled (eight times larger than the human genome) to understanding species interactions and research on artificial intelligence.

Yorke’s ability to contribute to such a broad range of disciplines comes from his unique ability to cut to the core of what matters. 

Seeing Through the Chaos 

Yorke came to UMD in 1963 as a graduate student after earning his bachelor’s degree in mathematics from Columbia University. He was attracted to the interdisciplinary work at the Institute for Fluid Dynamics and Applied Mathematics (IFDAM), which is now known as the Institute for Physical Science and Technology (IPST). He earned his Ph.D. in mathematics in 1966 and joined IFDAM as a faculty member. 

Yorke held a joint appointment in the Department of Mathematics beginning in 1976 and the Department of Physics since 2000. He also served as IPST director from 1981 to 2005 and as chair of the Department of Mathematics from 2007 to 2013. 

When Yorke began his career, mathematicians and scientists tended to think that all physical phenomena were predictable and cases that defied prediction were merely examples of flawed experiments. The idea that dynamical systems can be both guided by precise rules and yet remain unpredictable in the long run (such as weather, which is governed by the laws of physics), seemed to stand only in isolated situations.

In the early 1970s, a colleague gave Yorke a copy of a 1963 paper from the Journal of the Atmospheric Sciences that would lay the foundation for the rest of his career. The paper, by American mathematician and meteorologist Edward Norton Lorenz, focused on mathematical methods used in numerical weather forecast models. It derived three differential equations from a complicated atmospheric circulation system and showed how small changes to data fed into the equations could result in considerably different outcomes. It was a very narrowly focused paper that didn’t initially rattle scientific cages, but Yorke recognized that Lorenz’s equations described a phenomenon that was applicable to all complex, dynamical systems. 

“Lorenz’s 1963 paper was very insightful, but he hadn’t related it to the broader world,” Yorke said. “It didn't lead anybody to say, ‘Oh, maybe that's what's happening here.’ What I did was explain and generalize the phenomena that Lorenz’s paper described.”

Yorke also gave the phenomenon a name: chaos. In 1975, Yorke and his graduate student Tien-Yien Li published the explanation in an article titled “Period Three Implies Chaos,” in the journal American Mathematical Monthly.

Suddenly, there was a scientific principle to describe how a dynamic system could be so sensitive to small, random perturbations as to be unpredictable, and it opened the gates for scientists and mathematicians to investigate randomness and instability in everything from weather and fluid dynamics to financial markets and the spread of disease. 

“The last people to know about chaos were the scientists,” Yorke said. “Because we all know how small things can have a big effect on our lives.”

Chaos became a new branch of science well suited to exploiting the emergence of personal computers and might have evolved in a completely different direction or never come about at all if Yorke’s colleague had never handed him that paper by Lorenz. Or if Yorke had not seen the bigger picture in Lorenz’s work. 

“I am pretty good as a mathematical problem-solver, but there are much better problem-solvers,” Yorke explained. “I see connections between things which don't look connected to other people until after the fact, and then, they seem obvious.”

Yorke has been recognized for his work at the highest levels. In 1995, he was named Distinguished University Professor, the highest academic honor bestowed by UMD. In 2003, he was awarded the Japan Prize for finding universality in complex systems such as chaos and fractals. The Japan Prize, administered by the Emperor of Japan, carries nearly the prestige of the Fields Medal and the Nobel Prize. And in 2013, he was awarded the UMD President’s Medal. 

That same year, the rotunda of the Mathematics building (now called William E. Kirwan Hall) was named for Yorke in commemoration of his 50 years of scholarship and service to the university. The plaque memorializing the dedication includes a few quotes that summarize Yorke’s philosophy on life and mathematics, including one that was referenced more than once during his 80th birthday celebration: “A degree in mathematics is a license to explore the universe.”

Curiosity as a Driving Force 

It was an exploration of the universe that first drew Yorke to science. In the fourth grade, on a trip to the Hayden Planetarium in New York City, he fell in love with the solar system. It was the imagery of the planets that captivated him at first, perhaps spurred by his budding interest in photography. (Yorke’s father had a darkroom at that time, and Yorke’s passion for photography has carried on, with photographs he took hanging in the lower level of Kirwan Hall.)

The beauty of those solar system images at the planetarium also inspired Yorke to read about astronomy, which led to an interest in physics and mathematics. In college, Yorke discovered he wasn’t excited by lab experiments or finding solutions to problems. He wanted to look at problems in new ways, to take an alternative approach that made the solutions seem more obvious. 

“Doing physics experiments was like something equivalent to doing my tax returns,” he said. “I’m not really interested in solving problems, I’m interested in taking a problem and a method that don’t work together, and then you’ve got to change the problem and change the method until they work together.”

Perhaps just as central to Yorke’s success is his drive to root mathematics and physics in the tangible world and to apply his unique vision in areas that resonate with people outside of math and physics. 

“My goal is not to make discoveries that only the five smartest people in the world will understand,” Yorke said. “My goal is to tell physicists how to think about mathematics. I’m interested in examples that people can understand, and I’m always asking, ‘Can you come up with research that will surprise people?’”  

Call it curiosity or wonder, but even now the element of surprise seems to light a visible spark in Yorke’s eyes when he speaks. It’s as if he’s perpetually challenging the world to throw something new at him. 

As he said during his 80th birthday celebration, “The question is always, ‘What do we do next?’”

Written by Kimbra Cutlip

Brin Postdoctoral Fellow Agnieszka Zelerowicz took a chance by leaving Poland, and it set her on a challenging new path.

Brin Postdoctoral Fellow Agnieszka Zelerowicz was first drawn to mathematics in college when she discovered the theoretical side to math. 

“I was always good at math, but it was just not very interesting to me until I took some advanced courses,” Zelerowicz recalled. “It was intro to topology or something, and it was so different from anything else. I think the abstraction of it is what drew me in.”

While others in her class struggled with the more abstract subjects, Zelerowicz found they came easily to her, and she began to recognize her strength in mathematics. 

“Agnieszka has many original ideas and is not afraid to stand by them,” said Dmitry Dolgopyat, Zelerowicz’s mentor at the University of Maryland.

Zelerowicz is one of five Brin Postdoctoral Fellows who are supported by a generous gift from Mathematics Professor Emeritus Michael Brin. The Brin Postdoctoral program in UMD’s Department of Mathematics supports young mathematicians whose work shows remarkable promise in mathematical research.  

“Agnieszka shows curiosity and fearlessness in attacking new problems, which has led in a short time to a remarkable breadth in her research,” said UMD Mathematics Professor Giovanni Forni. “She has great technical skills and the ability to work very hard, qualities that are important to succeed in mathematical research. Among the promising aspects of her work, she has pushed the boundaries of fundamental tools to study chaotic systems using tools of geometry.”

Zelerowicz works in the area of ergodic theory and thermodynamic formalism. Both are areas of mathematics that focus on understanding dynamical systems. In mathematics, these systems can be described by determining the location in space of a given point at a given moment in time. (Think of models that predict the motion of a pendulum or the diffusion of a particle of smoke into a room). 

“This work is theoretical, and it deals with mathematical models, not physical objects,” Zelerowicz explained. “But it has very strong connections to physics, so it borders on being applied.”

One of the applications of the mathematics she works on can be useful in studying electricity and conductive metals. Imagine a billiard table where a tiny particle representing an electron bounces around between the billiard balls, which represent the atoms of metal. Although the electron’s behavior may look random, mathematics can describe the probability of the electron taking various paths depending on a variety of factors, such as where it originates, its velocity, the temperature in the room, among other things. Using these probabilities, mathematicians can build a model of the electron’s behavior under different conditions. 

Applying this idea, Zelerowicz is collaborating with Assistant Professor of Mathematics Rodrigo Trevino on a new model for studying how electricity moves through materials with long-range structure, such as certain types of crystals.

“It is challenging to find this middle ground in mathematics—to find a problem that would be difficult enough so that it would be interesting, but still something that is not impossible to solve,” she said. 

As Zelerowicz searches for her next problem to solve, she is also looking for her next career step after she completes her postdoctoral fellowship in summer 2022. She is investigating opportunities throughout the U.S., but also countries like Brazil. It’s a surprising twist for someone who never imagined living outside of Poland. 

Zelerowicz grew up in Rutki-Kossaki, a small town in Poland where her parents ran a bakery and her entire extended family has lived for generations. After high school, she went to the University of Bialystok in Poland and earned a bachelor’s degree in financial mathematics, followed by a master’s degree in mathematics in engineering from the Warsaw University of Technology. 

“I never really considered moving abroad, but when I was doing my master’s, I met a lot of people who were planning to study abroad or who already did study abroad,” Zelerowicz explained. “At first, I was almost startled by the whole idea, by the very thought of moving to a country where I was asked to speak a foreign language the whole time. I thought it would be very uncomfortable. But then over time I thought, ‘Wait, I'm just as smart as those other people.’”

When it came time to apply for her Ph.D., Zelerowicz threw just one arrow outside of Poland, aiming at The Pennsylvania State University. 

“I didn't even view it as a realistic goal,” she remembered. “I think I had all the intentions of staying in Poland. Applying to Penn State was just an experiment to see what would happen.”

Her arrow hit a bullseye, and she packed her bags and moved to Pennsylvania in 2013. After earning her Ph.D. in mathematics, she came to UMD in 2019. New to Maryland, Zelerowicz had a tough time when the COVID-19 pandemic hit in 2020. She hadn’t built her social network here, and she was unable to visit her family in Poland. To combat the isolation, Zelerowicz leaned into the physical fitness and outdoor activities she had come to love at Penn State, especially rock climbing.

“Climbing is a lot like solving a math problem in the way that you position your body and solve a challenging route,” she said. “Sometimes when certain transitions or moves on a route seem very hard and almost impossible, but then you change the angle of your body a little bit and move your foot a very little bit to the side, and then suddenly it becomes easy.”

In climbing, as in mathematics, things become easy only through hard work, ample technical skills and a bit of fearlessness—qualities that should help Zelerowicz continue to succeed in the years ahead. 

Written by Kimbra Cutlip

Ren uses statistics to make sense of a messy world.

Joan Jian-Jian Ren is a problem-solver. The University of Maryland mathematics professor develops tools to analyze large, messy biomedical datasets. Although much of her work delves deep into theoretical statistics, her research has real-world applications for helping make sense of the enormous volumes of data collected today.

“There are many situations where we don’t have methods to analyze the data that we have,” Ren said. “People are collecting huge volumes of data, but if we can’t analyze it properly, then we can’t really get useful information out of it or come to the most accurate possible conclusions.”

Take vaccination data, for example. The U.S. Department of Health and Human Services houses a database with more than a half-million reports on the adverse effects of vaccines but extracting a clear story from the data isn’t easy. 

“The structure of this data is very complex,” Ren said. “For example, when you take your kid to get vaccines, they will get maybe three or four shots at one time. So, when they get a fever or some other adverse reaction, how do we know which vaccine triggered it? Or, if the reaction comes three days or four later, how do we know what variables are involved in causing that reaction?”  

To answer those questions, Ren applies statistics and data visualization tools she develops with colleagues from the University of Michigan Medical School and the University of Maryland School of Medicine. They are beginning to find patterns that indicate which vaccines cause which types of reactions. Ren also develops statistical methodologies to better analyze and understand data on AIDS and certain cancers. Their findings may eventually help regulatory agencies set medical standards and make recommendations for treatments and preventions. 

That’s exactly what happened when Ren dug into the data on breast cancer screenings two decades ago. Scientists had been struggling to determine how frequently women needed to have mammograms and at what age to detect the earliest stages of breast cancer. Ren and colleagues from the University of Nijmegen in the Netherlands concluded that mammogram screenings once every two years was sufficient for early detection of breast cancer in women over 70 years of age, but not in women under 70. 

“Our research concluded that every two years was not frequent enough for detecting primary cancer in women under 70,” Ren said. “And it opened the debate about the appropriate frequency of screening mammograms in women under 70.”

Guidelines still vary widely among different institutions and agencies, but Ren’s work had real-world applications, because most recommendations suggest less frequent mammograms for women over 70. 

“I find it very exciting to use mathematics in a meaningful way that can really help people,” Ren said. “It is always rewarding to work on a challenging mathematics problem, and it makes me happy to see the significance and importance of the results.” 

Ren discovered the rewards of solving difficult math problems when she was still in high school in Beijing, China. She did well in mathematics competitions and often found herself helping friends work through challenging math problems. She enjoyed the feeling of being good at math, but when she realized it was something she wanted to pursue as a career, Ren had to navigate a critical non-mathematical problem.

“My mother really didn’t want me to study math,” Ren recalled. “In China, girls were not encouraged to do math. It was seen as something girls didn’t do.”

Ren was good at foreign languages and writing, and her mother tried to persuade her to become a translator or something more traditionally associated with women’s jobs in China. 

“That was a huge fight. It was a very difficult decision for me,” Ren remembered. “Then my high school math teacher got involved. He had a meeting with my mother, and she laid off after that.”

Thanks to her math teacher, Ren studied mathematics at Peking University. In 1985, she moved to the United States to earn her Ph.D. in theoretical statistics from the University of North Carolina at Chapel Hill. There, she found very different attitudes toward women in mathematics.

“One of the biggest differences when I came to this country is I felt that, overall, they supported women much more,” Ren said. “All my professors were very supportive, and I don’t feel that they treated me differently as a girl or that I didn’t belong in math because I was a girl.”

After earning her Ph.D. in 1990, Ren joined the faculty at the University of Nebraska–Lincoln and then moved to Tulane University and the University of Central Florida. She earned tenure in Nebraska and was a professor before coming to UMD in 2011.

“Her work in biostatistics was very exciting, and she was really an expert at what she was doing,” said UMD Mathematics Professor Benjamin Kedem, who recruited Ren to UMD. They met when she was giving an invited talk at an international statistics conference in Washington, D.C. 

“Jian-Jian’s work refined a well-known statistical model called the Cox proportional hazards model, and with her expertise and talent I knew it would be a benefit to the department to have her here,” Kedem said.

The Cox proportional hazards model is used in medicine to determine survival rates or hazard risks (such as a person’s risk of dying of cardiovascular disease over the next five or 10 years) based on different variables. 

The move to Maryland turned out to be a good decision for Ren and her young son. The department welcomed her warmly and supported her work, and her son was able to excel in the local school system. He will soon graduate from UMD with a B.S. in mathematics at just 19 years old. 

As a soon-to-be empty-nester, Ren may have more time for playing tennis and piano. But one thing is certain, she will continue to be motivated by the big questions that lie hidden in biomedical data, just waiting for someone like her to help tease out the answers. 

“Statistics is only going to become more and more important in the era of big data,” Ren said. “I would love to see more statisticians here at Maryland working with experts from other departments to understand how to analyze and understand the data. There are a lot of problems big data can help solve but only with the right tools.”

Written by Kimbra Cutlip

An internationally renowned mathematician in probability theory, Freidlin was once a Russian “refusenik.”

After more than 30 years at the University of Maryland, Distinguished University Professor Emeritus of Mathematics Mark Freidlin retired on July 1, 2021. After being barred from leaving his home country 40 years ago and shut out of academic life for nearly a decade, Freidlin moved to Maryland and traveled the world as an invited speaker at prestigious mathematical conferences and research institutions. 

Freidlin was born in Moscow and began his career in mathematics during the Cold War between the United States and the former Soviet Union. As a professor of mathematics at Moscow State University in the 1960s and ’70s, Freidlin earned both privilege and status in a country that valued higher education and revered rigorous intellectual pursuits. 

But as a person of Jewish descent, Freidlin was also subjected to government harassment, discrimination and policies that limited his professional and economic opportunities. He applied for an exit visa in 1979 with hopes of leaving the Soviet Union with his wife, Lera, who was also a mathematician, and their two children. They were denied an exit visa without an explanation, and they were promptly fired from their jobs and barred from publishing papers in the Soviet Union or attending scientific conferences. 

During those years, the Soviet Union ran a brutal political campaign to separate its citizens and citizens from other East bloc countries from the Western world behind what Winston Churchill called the Iron Curtain. Scientists and mathematicians were often denied permission to leave the country. After Freidlin and his wife requested permission to emigrate, they were labeled “refuseniks”—Soviet citizens denied the freedom to leave their country by the Soviet government. Freidlin was 41 years old.

For eight years, Freidlin and his wife made a living as tutors. Lera also got work translating documents, and Freidlin continued working on mathematics on his own. But he had already earned an international reputation, in part because of a book he and his colleague Alexander Wentzell published right before he was shut out of academia.

“I waited until after the book was published to apply for an exit visa, because I knew if I applied before, the book would never be published,” Freidlin recalled.

The book was first published in Russian in 1979 and was translated into English in 1984. Several editions followed, with the latest published in 2012. The book introduced a theory, now known as the Freidlin-Wentzell theory, which explains how small, seemingly insignificant, perturbations in complicated systems can create critical changes in the system over long time periods. The theory is widely used in mathematical modeling in fields as diverse as physics, biology, economics, and the social sciences.

The Freidlin-Wentzell theory laid the groundwork for much of his later research that seeks to describe the effects of small random fluctuations on dynamical systems. 

“In many mathematical models, if you don’t take into account random perturbations in the system, that may work fine over certain time intervals,” Freidlin explained. “But over longer time intervals, these perturbations can become critical enough to cause a transition from one stable behavior to another stable behavior, and our goal is to describe these transitions.” 

Freidlin would eventually work with Wentzell again, years after the Soviet Union fell and they were both in the U.S., but in the eight years between publication of his first book and his arrival in Maryland, Freidlin was forced to work largely on his own. During that time, his western colleagues helped Freidlin communicate with the outside world. 

Visiting colleagues smuggled Freidlin’s letters and academic papers out of the country, and he remained an important figure in the world of mathematics, publishing several papers in academic journals outside of the Soviet Union during his time as a refusenik.

But those papers represented just a fraction of Freidlin’s work during those years, so he compiled his unpublished works into a second book that his wife translated into English. They had it smuggled out of the country, and his former Ph.D. advisor Eugene Dynkin arranged for it to be published through Princeton University Press. Dynkin left the Soviet Union in 1977 and was teaching mathematics at Cornell University. 

“A colleague carried it out of the country,” Freidlin recalled. “We changed the cover page to make it look as if he was the author of the book so that if he was caught it would not appear to be mine.”

Freidlin’s second book “Functional Integration and Partial Differential Equations” was published in 1985. Two years later, under pressure from the international community, the Soviet government granted Freidlin and his family permission to leave. He and Lera packed up their two children and moved to Maryland in 1987.

“I had some other offers from different countries,” Freidlin recalled, “but various colleagues including Dynkin convinced me to go to Maryland.” 

Lera took a job as a statistician at the National Institutes of Health. And after waiting so many years to leave his homeland, Freidlin embarked on a few years of travel to share his mathematical ideas as an invited speaker in France, Israel, Germany, Italy, England, Canada, and all over the U.S. He was even an invited speaker at the International Congress of Mathematicians in 1998.   

“After eight years, we were happy to come to the United States,” he said. “I had liked to teach students, and I enjoyed teaching again and being able to travel and talk with colleagues openly. I was very happy.” 

During his tenure at UMD, Freidlin mentored more than a dozen Ph.D. students and several postdoctoral associates. He has given more than 170 invited talks around the world and published nearly 100 refereed papers (making a combined total exceeding 150 papers over the course of his career). 

Through these works, Freidlin made prolific contributions to the field of stochastics, which is the study of complex processes that can be analyzed and predicted statistically but defy prediction of precise outcomes. 

“I was very lucky to be a mathematician,” Freidlin said. “It is very interesting work, and it’s a world where you can live outside these other problems you know. There is always something interesting in mathematics that you can be challenged to think about and to solve.” 

Freidlin will continue to work on mathematical theories in his retirement and spend more time with his grandchildren. He also looks forward to resuming travel once the threat of COVID-19 is in the rearview mirror. Hopefully, he should not have to wait eight years.

Written by Kimbra Cutlip

We welcomed six new faculty members and five Novikov postdocs to the Math family this fall!

Faculty:

Lei Chen (Assistant Professor). Lei received a B.S. from Peking University and a Ph.D. from the University of Chicago (2018) under the supervision of Benson Farb. She was then a Noether Instructor at CalTech. Lei works in the area of low dimensional topology and geometric group theory.  She made major contributions in the areas of group actions on manifolds and homomorphisms between transformation and mapping class groups. Her work is also related to complex geometry and topological dynamics.

Dan Cristofaro-Gardiner (Assistant Professor). Dan received his A.B. degree from Harvard (2007) and Ph.D. from Berkeley (2013). He then worked as an assistant professor at UC Santa Cruz and was a von Neumann Fellow at the Institute for Advanced Study. Dan works in symplectic topology/geometry/dynamics. He is a leader in the field of “quantitative symplectic geometry,” an area that focuses on questions about symplectic embedding of symplectic manifolds with boundary, and Reeb dynamics on the boundaries of symplectic manifolds. He has contributed in substantial ways to a variety of hard problems. Most recently, together with Humiliere and Seyfaddini, he posted on the arXiv a surprising proof of the simplicity conjecture showing that the group of compactly supported area-preserving homeomorphisms of the two-disc is not simple.

Bassam Fayad (Professor, Brin Chair). Bassam received his Ph.D. from the École Polytechnique (2000) and a Habilitation from the University of Paris 13 (2006). Recently, he worked as a Directeur de Recherche 1ère class at the CNRS. Bassam is a distinguished mathematician, working in the area of dynamical systems. He is mostly known for his work on the Kolmogorov-Arnold-Moser (KAM) theory. Bassam’s work is centered on Hamiltonian dynamics and on smooth ergodic theory. He has important results in many other areas including rigidity theory, number theory and mathematical physics. Bassam made substantial contributions to the KAM theory of analytic systems by proving stability results and obtaining optimal bounds for the stability time. Among other areas, he obtained significant results in the study of positive entropy systems and to zero entropy systems. Throughout his career, Bassam has received many distinctions and honors, including an invited lecture at the 2018 International Congress of Mathematics in Rio de Janeiro. Bassam joins our department as the Michael and Eugenia Brin Distinguished Chair of Mathematics.

Yu Gu (Associate Professor). Yu received a B.S. in mathematics and physics from Tsinghua, an M.S. from Brown and a Ph.D. from Columbia under the direction of Guillaume Bal. He then spent three years as a Szegö Assistant Professor at Stanford before moving to Carnegie Mellon University as an assistant professor (2017). Yu works in the area of mathematical and asymptotic analysis of random dynamics and random partial differential equations. He made fundamental contributions to the theory of homogenization and provided the first results on random fluctuations in high dimensions. Recently, he obtained breakthrough results in the study of a Hamilton-Jacobi type equation driven by a spacetime white noise, the so-called KPZ equation. Last year, Yu received a National Science Foundation CAREER Award.

Huy Nguyen (Assistant Professor). Huy received a Ph.D. from the University of Paris-Sud 11 (with Nicolas Burg, 2016). Then, he was a postdoc in Princeton and a Tamarkin Assistant Professor at Brown. Huy works in the area of analysis, somewhere between pure analysis, harmonic analysis, and PDEs.  Huy made substantial contributions to many problems including the proof of modulation instability of Stokes waves, optimal Strichartz estimate for water waves, and the global well-posedness for the one-phase Muskat problem (a free boundary problem in a porous medium that describes two flows separated by a free boundary).

Christian Rosendal (Professor). Christian received a Ph.D. from the University of Paris 6 under the direction of Alain Louveau. He then worked at CalTech, the University of Illinois at Urbana-Champaign, and more recently at the University of Illinois at Chicago. In the past two years, he has been working as a program director at the National Science Foundation. Christian works in the area of mathematical logic. His research belongs to four interconnected topics: rigidity of Polish groups, geometry of topological groups, descriptive set theory, and the geometry of Banach spaces. In 2020, he was named Fellow of the AMS.

Novikov Postdocs:

James Hanson. A student of Uri Andrews at Wisconsin. James works in continuous logic and applications of logic to topology and analysis. He also has a background in theoretical physics. His mentor is Chris Laskowski.

Xiaoqi Huang. A student of Chris Sogge at Johns Hopkins. Xiaoqi works in harmonic and geometric analysis and partial differential equations. His mentor is Manos Grillakis.

Hussain Ibdah. A student of Edriss Titi at Texas A&M. Hussain is interested in theoretically analyzing nonlinear, nonlocal PDEs, in particular, those of fluid mechanics and transport-diffusion systems. His mentor is Eitan Tadmor.

Rigoberto Zelada. A student of Vitaly Bergelson at Ohio State. Rigoberto works in ergodic theory. His mentor is Adam Kanigowski.

Lutian Zhao. A student of Sheldon Katz at Illinois. Lutian works in enumerative algerbraic geometry with applications to mathematical physics. His mentor is Amin Gholampour.