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Caltech

Joint Los Angeles Topology Seminar

Monday, February 3, 2025
5:00pm to 6:00pm
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Linde Hall 310
Irreducible 4-manifolds can admit exotic diffeomorphisms
Hokuto Konno, Graduate School of Mathematical Sciences, University of Tokyo,

A diffeomorphism of a smooth manifold is called an exotic diffeomorphism if it is topologically isotopic to the identity but smoothly not. Since Ruberman's pioneering work in 1998, extensive research has been conducted to the detection of exotic diffeomorphisms of 4-manifolds, with particularly active developments in recent years. Nevertheless, the basic question of whether an irreducible 4-manifold can admit an exotic diffeomorphism has remained a major unresolved problem in the field. We resolve this open problem affirmatively by providing numerous examples of minimal complex surfaces that admit exotic diffeomorphisms. This is joint work with David Baraglia.

For more information, please contact Math Department by phone at 626-395-4335 or by email at mathinfo@caltech.edu.