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Algebraic Geometry Seminar
Seminar information archive ～12/01｜Next seminar｜Future seminars 12/02～
| Date, time & place | Friday 13:30 - 15:00 118Room #118 (Graduate School of Math. Sci. Bldg.) |
|---|---|
| Organizer(s) | GONGYO Yoshinori, KAWAKAMI Tatsuro, ENOKIZONO Makoto |
Future seminars
2025/12/19
13:30-15:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Hokuto Konno (University of Tokyo)
On diffeomorphisms of complex surfaces
Hokuto Konno (University of Tokyo)
On diffeomorphisms of complex surfaces
[ Abstract ]
Many basic questions about the diffeomorphism groups of complex surfaces remain unresolved. For example, until recently it was unknown whether there exists a simply-connected complex surface admitting a diffeomorphism that acts trivially on the intersection form but is not isotopic to the identity. We have recently answered this question by showing that certain elliptic surfaces do admit such diffeomorphisms. These diffeomorphisms are obtained as suitable compositions of reflections along (-2)-curves. Moreover, this result also provides a negative answer to a question of Donaldson in symplectic geometry. This talk is based on joint work with David Baraglia, and with Jianfeng Lin, Anubhav Mukherjee, and Juan Muñoz-Echániz.
Many basic questions about the diffeomorphism groups of complex surfaces remain unresolved. For example, until recently it was unknown whether there exists a simply-connected complex surface admitting a diffeomorphism that acts trivially on the intersection form but is not isotopic to the identity. We have recently answered this question by showing that certain elliptic surfaces do admit such diffeomorphisms. These diffeomorphisms are obtained as suitable compositions of reflections along (-2)-curves. Moreover, this result also provides a negative answer to a question of Donaldson in symplectic geometry. This talk is based on joint work with David Baraglia, and with Jianfeng Lin, Anubhav Mukherjee, and Juan Muñoz-Echániz.
2025/12/26
13:30-15:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Nao Moriyama (Kyoto University)
TBA
Nao Moriyama (Kyoto University)
TBA
2026/01/16
13:30-15:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Ryu Tomonaga (University of Tokyo)
TBA
Ryu Tomonaga (University of Tokyo)
TBA
