Ring of Continuous Real-Valued Functions is Ring

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Theorem

Let $\struct {S, \tau}$ be a topological space.

Let $\R$ denote the real number line.

Let $\struct {\map C {S, \R}, +, *}$ be the ring of continuous real-valued functions from $S$.


Then:

$\struct {\map C {S, \R}, +, *}$ is a ring


Proof

By definition of ring of continuous real-valued functions:

$\struct {\map C {S, \R}, +, *}$ is the ring of continuous mappings from $S$ to $\R$.

From Ring of Continuous Mappings is Subring of All Mappings:

$\struct {\map C {S, \R}, +, *}$ is a subring

By definition of subring:

$\struct {\map C {S, \R}, +, *}$ is a ring

$\blacksquare$


Also see


Sources

1960: Leonard Gillman and Meyer Jerison: Rings of Continuous Functions: Chapter $1$: Functions on a Topological Space, $\S 1.3$