MathGloss

A norm on a vector space VV is a real-valued functional \vert \vert \cdot\vert \vert such that for all v,wVv,w \in V and αR\alpha \in \mathbb R, the following properties hold:

  1. v+wv+w\vert \vert v+w\vert \vert \leq \vert \vert v\vert \vert + \vert \vert w\vert \vert ;
  2. αv=αv\vert \vert \alpha v\vert \vert = \vert \alpha\vert \cdot \vert \vert v\vert \vert ;
  3. v0\vert \vert v\vert \vert \geq 0 and v=0\vert \vert v\vert \vert = 0 if and only if v=0v=0.

Wikidata ID: Q956437