Toshiyuki KOBAYASHI

Toshiyuki Kobayashi is a Professor at the Graduate School of Mathematical Sciences, The University of Tokyo. His research focuses on Lie theory, unitary representation theory, non-commutative harmonic analysis, and discontinuous groups. He has co-authored foundational works on minimal representations and symmetry breaking operators, and serves as vice director of the French-Japanese Laboratory of Mathematics and its Interactions (FJLMI). Academic service includes editor roles for Japanese Journal of Mathematics, International Mathematics Research Notices, and the Takagi Lectures series.

Research Interests:

• Visible actions on symmetric spaces and complex manifolds
• Spectral analysis on non-Riemannian locally symmetric spaces
• Branching problems in representation theory
• Conformal geometry and differential operators
• Applications to special functions and quantum theory

Scientific Contributions:

• Developed a framework for symmetry breaking operators in indefinite orthogonal groups
• Unified geometric and representation-theoretic approaches to minimal representations
• Provided criteria for compact quotients of homogeneous spaces
• Generalized Cartan decomposition via visible actions

Awards:

• Festschrift (2025)
• Doctorat Honoris Causa, University of Reims (2022)
• AMS Fellow (2017)
• Humboldt Research Award (2008)
• Takebe Prize (1997)

Students and Collaborators:

• Advised over 40 students including Kazuki Kannaka, Víctor Pérez-Valdés, and Koichi Tojo
• Collaborators include Fanny Kassel, Gen Mano, and Bent Ørsted