T3.5
Description: If $A$ is a closed subset of $X$ and $b$ is a point not in $A$, there is a Urysohn function for $A$ and $\{b\}$. (That is, there is a continuous function $f: X \to [0,1]$ such that $f(A) = \{1\}$ and $f(b) = 0$.)
Description: If $A$ is a closed subset of $X$ and $b$ is a point not in $A$, there is a Urysohn function for $A$ and $\{b\}$. (That is, there is a continuous function $f: X \to [0,1]$ such that $f(A) = \{1\}$ and $f(b) = 0$.)