A Look Back at the Second Summer School 2025

The second summer school of 2025, held at IHES from July 7 to 18, brought together an international community of early-career researchers to explore themes related to discrete subgroups of Lie groups. Organized by David Fisher (Rice University), Fanny Kassel (CNRS & IHES), Ralf Spatzier (University of Michigan) and Matthew Stover (Temple University), the school focused on major recent breakthroughs in the field.

“It was a real pleasure to organize this summer school. Participants made the most of the beautiful surroundings at IHES. All the minicourses were excellent — the speakers did an outstanding job,” said Fanny Kassel, one of the event’s co-organizers.

Through a series of minicourses, the school offered a broad introduction to several contemporary aspects of research on discrete subgroups of Lie groups. The courses were led by distinguished experts recognized both for their scientific excellence and pedagogical talent. Lecturers included Simion Filip (University of Chicago), Homin Lee (Northwestern University), Sam Mellick (Jagiellonian University), Amanda Wilkens (Carnegie Mellon University), Daniel Monclair (Université Paris-Saclay), Maria Beatrice Pozzetti (Università di Bologna), Roman Sauer (Karlsruher Institut für Technologie), Barbara Schapira (IMAG, Université de Montpellier), Antoine Song (California Institute of Technology) et Nattalie Tamam (Imperial College London). Their contributions allowed participants to explore a wide range of topics.

The primary goal of the event was to give young mathematicians access to these recent developments, while fostering an environment conducive to scientific exchange and the emergence of new collaborations.

Shunsuke Miyanchi, a first-year PhD student at the University of Tokyo, emphasized the school’s significance:

“I study proper actions on homogeneous spaces, and thanks to recent developments, some very interesting connections with the theory of Anosov representation have emerged. This theory is less known in Japan, which is one of the main reasons I am very happy to have come here: to better understand the current state of research in this field, deepen my knowledge, and engage with researchers working on related topics.”

For those who were unable to attend, recordings of the lectures are available on the IHES YouTube channel.

IHES warmly thanks Clay Mathematics Institute, Engie, the FMJH Fondation, U.S. National Science Foundation, Qube Research & Technologies and Société Générale for their generous support of this summer school.