TheoremBase

Uniform Continuity Along a Compact Subset of the Domain

Statement

Let (X,d)(X,d) be a metric space, equipped with the collection of all subsets open in (X,d)(X,d), which is a topology by The Open Subsets of a Metric Space Form a Topology. Let R\mathbb{R} be the real numbers with the order ≤\le of their ordered field structure, write s<ts<t to mean that s≤ts\le t and s≠ts\ne t, let ∣s∣|s| be the absolute value of ss, and let dRd_{\mathbb{R}} be given by dR(s,t)=∣s−t∣d_{\mathbb{R}}(s,t)=|s-t|, a metric on R\mathbb{R} by The Absolute Value Metric on the Real Numbers.

Let Ω⊆X\Omega\subseteq X be open in (X,d)(X,d), let K⊆ΩK\subseteq\Omega be compact in XX, and let f:Ω→Rf:\Omega\to\mathbb{R} be continuous on Ω\Omega as a map from (X,d)(X,d) into (R,dR)(\mathbb{R},d_{\mathbb{R}}).

Then for every η∈R\eta\in\mathbb{R} with 0<η0<\eta there is θ∈R\theta\in\mathbb{R} with 0<θ0<\theta such that

∣f(z)−f(x)∣<η|f(z)-f(x)|<\eta

for every x∈Kx\in K and every z∈Ωz\in\Omega with d(x,z)<θd(x,z)<\theta.

Note that zz is required only to lie in Ω\Omega, not in KK.

Proofs

Log in to submit a proof.

Loading...

Citations

Loading…

Dependencies

Loading…

Related

0 relations

Curated associations between results. These are editable and subjective — they do not replace the dependency graph, which is derived from the references in the text.

No relations recorded yet.

Comments

Log in to comment.

Loading…