FIND ME ON

GitHub

LinkedIn

Arzelà-Ascoli

🌱

Theorem
Analysis

Totally Bounded

Let (X,d)(X,d) be a Compact Metric Space and FC(X)F \subset C(X). Then F is Totally Bounded for dsupd_{sup} if and only if it is uniformly bounded and Equicontinuous, thus uniformly equicontinuous, i.e. ϵ>0\forall\epsilon>0 F<:fC(X),gF:supxXf(x)g(x)<ϵ    δ>0:d(x,y)<δ    f(x)f(y)<ϵ,fF\begin{gather*} |F|<\infty:\forall f \in C(X),\exists g\in F : \sup_{x \in \mathbb{X}}|f(x)-g(x)|<\epsilon\\ \iff\\ \exists\delta>0:d(x,y)<\delta\implies|f(x)-f(y)|<\epsilon,\forall f\in \mathscr{F} \end{gather*}