ScalingStacks

Verified tagged author-source HTML · 1904.03696v1 · cited publication edition alignment unverified.

00HH

Lemma 2.13. Let (V,∥⋅∥)(V,\lVert\mathord{\cdot}\rVert) be a finite-dimensional ultrametrically normed vector space over kk. If {vi}i∈{1,…,n}\{v_{i}\}_{i\in\{1,\dots,n\}} is a finite set of elements of VV such that {∥vi∥}i∈{1,…,n}\{\lVert v_{i}\rVert\}_{i\in\{1,\dots,n\}} are disctinct in ℝ+\mathbb{R}_{+}. Then ∥∑i∈{1,…,n}vi∥=maxi∈{1,…,n}⁡∥vi∥\lVert\sum_{i\in\{1,\dots,n\}}v_{i}\rVert=\max_{i\in\{1,\dots,n\}}\lVert v_{i}\rVert.

00HI

Proof. If n=2n=2, this is clear from the ultra-metric inequality. For general nn an induction argument shows the equality. ∎

Original mathematics by the credited authors. Source collection and HTML conversion remain in progress.