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7 years, 8 months ago
Let $X$ be a finite dimensional (possibly compact) Alexandrov space with curvature $\geq K$.
Is it true that its boundary is again Alexandrov space with curvature bounded from below? If yes, is the curvature at least $K$?
Oct 1, 2015 at 8:27
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This is an open problem.
It is a special case of the following question:
Is it true that every extremal subset is again an Alexandrov space?
The answer to this question is "No". Petrunin has constructed a counterexample in codimension three,
Oct 1, 2015 at 9:55
John Harvey John Harvey
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