Sara van de Geer: farewell lecture

Laudation by Robert Weismantel, Head of Department:

It is my pleasure to chair this farewell lecture of Sara van de Geer.

Sara has been a full professor at ETH since 2005. She was born in Leiden, in the Netherlands, where she also studied mathematics and obtained her PhD degree in 1987. Before her time at ETH she held several positions: she was a lecturer in Bristol, a scientific employee at CWI in Amsterdam, an assistant professor in Utrecht and Leiden, an associate professor in Toulouse and a full professor in Leiden. And then she finally came to Zurich and since 2005 she has been with us.

A few words about her research: Sara is working in the foundations of mathematical statistics. In her research she strives to formulate unifying principles for statistical theory and modeling. Her motivation lies in revealing the theoretical foundations of existing popular methods and algorithms, and typically the models she studies are over parametrized ones where one needs to use regularization to avoid overfitting. She became famous for many works but in particular I want to mention her works on entropy-​based bounds for regularized estimators and her works about sparsity-inducing regularization. Her recent work concentrates on regularization with total variation type norms, the behaviour of stationary points of empirical risk functions, the topic of inference in general and in particular lower bound construction is something that she likes very much.

Sara has received many awards and distinctions. She was an invited speaker at the International Congress of Mathematicians in India in 2010. She is a member of several academies of science: the Leopoldina, the Royal Dutch Academy of Science, and since this year a member of the US National Academy of Science.

Sara is a wonderful colleague. It is really hard to believe that she is retiring. She served as a chair of the Seminar of Statistics for many years. She was in many committees – always present when there were difficult things to solve. I also want to mention her work in the SNSF: she has been a Forschungsrat for several years and she was very often in Bern and involved in all kinds of activities for the Swiss National Science Foundation.

To give you an example of how nice Sara is: When I came to ETH in 2010, I was in contact with Sara because we both had to fly to India. Sara came to my office and said to me: "You know what? You need a visa for India." And then she said: "Well, I also need a visa, but if you give me your passport I'll take care of it, because I have to go to Bern, there's a meeting with the Swiss National Science Foundation. I'll take your passport and mine and go to the Indian Embassy". So she got the visa for the two of us and that is how we met. This is just a little example, but it shows how generous and nice Sara is.

Thank you very much for all that you have done!