:PROPERTIES: :ID: 9a1cc2d9-ef99-436c-8c21-9e68fd7df192 :END: #+title: normed vector space #+author: Preston Pan #+html_head: #+html_head: #+html_head: #+options: broken-links:t * Introduction A normed vector space is a [[id:ab024db7-6903-48ee-98fc-b2a228709c04][vector space]] with a norm defined, which describes the "length" of the vector. This norm obeys these properties: \begin{align} \label{} \lVert ax \rVert = \lvert a \rvert \lVert x \rVert \\ \lVert x + y \rVert \le \lVert x \rVert + \lVert y \rVert \end{align} this gives rise to a [[id:6f24f731-60e5-4904-88d7-c63869505981][metric]] $d(x, y)$: \begin{align} \label{} d(x, y) = \lVert x - y \rVert \end{align}