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Asymptotic Midpoint Uniform Convexity


Asymptotic midpoint uniform convexity of a norm N on an infinite-dimensional Banach space X is positivity of its asymptotic two-sided midpoint modulus for every t>0. An averaged convention is

 delta^^_N(t)=inf_(N(x)=1)sup_(F in F)inf_(y in F
N(y)=1)((N(x+ty)+N(x-ty))/2-1),

where F consists of the closed linear subspaces of finite codimension. The standard maximum-based modulus replaces the average of the two norms by their maximum. If that modulus is m_N(t), then m_N(t)/2<=delta^^_N(t)<=m_N(t), so the positivity conditions agree. The property is abbreviated AMUC, and concerns the given norm; existence of an equivalent asymptotically uniformly convex norm is a separate question.


See also

Asymptotic Uniform Convexity, Banach Space, Daugavet Property, James Tree Space, Reflexive Space, Uniformly Convex

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References

Dilworth, S. J.; Kutzarova, D.; Randrianarivony, N. L.; Revalski, J. P.; and Zhivkov, N. V. "Lenses and Asymptotic Midpoint Uniform Convexity." J. Math. Anal. Appl. 436, 810-821, 2016. https://doi.org/10.1016/j.jmaa.2015.11.061.

Cite this as:

Weisstein, Eric W. "Asymptotic Midpoint Uniform Convexity." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/AsymptoticMidpointUniformConvexity.html

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