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arXiv · 0805.0314

Sums of norm spheres are norm shells and lower triangle inequalities are sharp

Lutz Mattner
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Abstract

The statements in the title are explained and proved, as a little exercise in elementary normed vector space theory at the level of Chapter 5 of Dieudonné's "Foundations of Mathematical Analysis". A connection to recent moment bounds for submartingales is sketched.

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Lutz Mattner. 2009-09-01. Sums of norm spheres are norm shells and lower triangle inequalities are sharp. https://arxiv.org/abs/0805.0314

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