# Totally Separated Space is Totally Disconnected

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## Theorem

Let $T = \struct {S, \tau}$ be a topological space which is totally separated.

Then $T$ is totally disconnected.

## Proof

Let $T = \struct {S, \tau}$ be a totally separated space.

Then for every $x, y \in S: x \ne y$ there exists a partition $U \mid V$ of $T$ such that $x \in U, y \in V$.

Suppose $T$ were not totally disconnected.

Then $\exists H \subseteq S: x, y \in U$ such that $H$ is connected.

But by definition of connected, there can be no partition $U \mid V$ of $T$ such that $x \in U, y \in V$.

Hence the result.

$\blacksquare$

## Sources

- 1978: Lynn Arthur Steen and J. Arthur Seebach, Jr.:
*Counterexamples in Topology*(2nd ed.) ... (previous) ... (next): Part $\text I$: Basic Definitions: Section $4$: Connectedness: Disconnectedness