Topic: Urysohn's Lemma and the Tietze Extension Theorem

Zero Sets and Cozero Sets of Continuous Functions

Worked Tietze Extensions on Intervals and Finite Sets

Tietze Extension for Complex-Valued Functions

The Geometric-Series Proof of Tietze Extension

The Closed-Set Shrinking Lemma in Normal Spaces

The Bounded Tietze Extension Theorem

Rescaling Urysohn Functions to Prescribed Values

Proving Continuity of the Urysohn Function

Preserving Bounds in Tietze Extensions

Nested Open Neighborhoods for Urysohn’s Lemma