Orateur(s)  Richard Bamler  UCBerkeley,

Titre  Compactness and partial regularity theory of Ricci ows in higher dimensions 
Date  03/03/2021 
Horaire  15:45 à 17:00 

Diffusion  
Résume  We present a new compactness theory of Ricci flows. This theory states that any sequence of Ricci flows that is pointed in an appropriate sense, subsequentially converges to a synthetic flow. Under a natural noncollapsing condition, this limiting flow is smooth on the complement of a singular set of parabolic codimension at least 4.We furthermore obtain a stratification of the singular set with optimal dimensional bounds depending on the symmetries of the tangent flows. Our methods also imply the correspondingquantitative stratifiation result and the expected L^pcurvature bounds.
As an application we obtain a description of the singularity formation at the first singular time and a longtime characterization of immortal flows, which generalizes the thickthin decomposition in dimension 3.We also obtain a backwards pseudolocality theorem and discuss several other applications. 
Salle  Demander le lien Zoom à olivier.biquard@sorbonneuniversite.fr 
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