Pseudo-isotopy versus isotopy for homeomorphisms of 4-manifolds

Isacco Nonino (University of Glasgow)

Monday 16th February 15:00-16:00
Maths 311B

Abstract

In joint work with Daniel Galvin, we define obstructions which obstruct topological pseudo-isotopies from being isotopic to isotopies in dimension four. These match the smooth obstructions of Hatcher-Wagoner for smooth pseudo-isotopies and accordingly are valued in certain Whitehead groups. Our definition fills a longstanding gap in the study of pseudo-isotopy spaces and allows to construct interesting examples of homeomorphisms that are pseudo-isotopic but not isotopic to the identity.

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