Abschiedsvorlesung Giovanni Felder

Dear Giovanni, dear Vice President, dear family and friends, ladies and gentlemen,

It is my great pleasure to welcome you to Giovanni Felder's farewell lecture.

Giovanni was born in Aarau in 1958, but attended high school in sunny Lugano south of the Gotthard. To this day, Giovanni is well connected with the high school landscape in Ticino, which he supports with lectures and committee work. Giovanni went on to study physics at ETH Zurich. In 1986 he completed his studies with the doctoral thesis supervised by Juerg Froehlich on "Renormalization group, tree expansion, and non-renormalizable quantum field theories", a topic which is well connected to recent advances in the theory of regularity structures advocated, for example, by the Fields medallist Martin Hairer.

His postdoctoral years brought him to the Institut des Hautes Études Scientifique in Paris, to the Institute for Advanced Study in Princeton and then back to the Department of Physics at ETH Zurich. After a short stay at University of North Carolina from 1994 to 1996, Giovanni returned as a full professor of mathematics to ETH Zurich.

Giovanni has written many influential works in mathematical physics. His vision includes both directions: analysing mathematical foundations of physical theories, and using concepts as well as intuition from physics to develop mathematical insights. In a joint work with Markus Engeli for instance they prove the Riemann-Roch-Hirzebruch formula for arbitrary differential operators, a deep mathematical result and a cornerstone of mathematical culture, by building on insights from quantisation theory and quantum field theory.

Let me highlight some further aspects of Giovanni's unique career trajectory: he was an invited Section speaker at the International Congress of Mathematicians in Zurich 1994, he is an elected member of several prestigious academies, he supervised 22 doctoral students including one of our esteemed colleagues at D-MATH, Thomas Willwacher and – last but not least, and very important to mention – Giovanni supported the communities by his organisational wisdom and his diplomatic esprit. He was Head of Department of D-MATH for two years – he introduced my inaugural lecture 14 years ago. He was director of the Institute for Theoretical Studies for six years and co-director of the NCCR SwissMAP for eight years.

Of course he continues to be a good citizen after his retirement – as he told me yesterday over lunch – and of course he continues to do fantastic research. His last preprint "Wild orbits and generalised singularity modules: stratifications and quantisation" is less than three weeks old and legendary 112 pages long – almost like a young and wild mathematician.

We are very much looking forward to Giovanni's farewell lecture.