Bounded Turning and Quasiconformal Maps.
The best constant in the Hyers-Ulam theorem on isometric approximation in Hilbert spaces is equal to the Jung constant of the space.
We improve the Mazur-Ulam theorem by relaxing the surjectivity condition.
We prove that every compact C-submanifold of R, with or without boundary, has the bilipschitz extension property in R.
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