Uniform continuity

Level UniversityDifficulty ★★★★★Concept⌖ Open in the map

What is it?

Continuity where one δ\delta works for every point at once. On a closed bounded interval every continuous function is uniformly continuous (Heine–Cantor), which makes approximation results such as Weierstrass's theorem possible.

Formulas

∀ε>0 ∃δ>0 ∀x,y: ∣x−y∣<δ⇒∣f(x)−f(y)∣<ε\forall\varepsilon > 0\ \exists\delta > 0\ \forall x, y:\ |x - y| < \delta \Rightarrow |f(x) - f(y)| < \varepsilon

Where it shows up in AI

  • Neural networks★★★★★advancedAI and machine learning

    Proofs of the universal approximation theorem use uniform continuity on compact sets.

Where is it used?

Computing topics reachable from here, through the chain of ideas that leads to them:

What depends on it

This page has the essentials. A fuller treatment (intuition, formal definition, worked example) is on the way.

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