Sharafutdinov's retraction

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In mathematics, Sharafutdinov's retraction is a construction that gives a

retraction of an open non-negatively curved Riemannian manifold
onto its soul.

It was first used by

isometric.[1] Perelman later showed that in this setting, Sharafutdinov's retraction is in fact a submersion, thereby essentially settling the soul conjecture.[2]

For open non-negatively curved Alexandrov space, Perelman also showed that there exists a Sharafutdinov retraction from the entire space to the soul. However it is not yet known whether this retraction is

submetry
or not.

References