# Hausdorffness is refining-preserved

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This article gives the statement, and possibly proof, of a topological space property (i.e., Hausdorff space) satisfying a topological space metaproperty (i.e., refining-preserved property of topological spaces)
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## Statement

### Property-theoretic statement

The property of topological spaces of being a Hausdorff space

### Statement with symbols

Suppose $(X,\tau)$ is a topological space and $\tau'$ is a finer topology on $X$ than $\tau$.

## Proof

Given: A Hausdorff topological space $(X,\tau)$, and a topology $\tau'$ on $X$ that is finer than $\tau$

To prove: $(X,\tau')$ is Hausdorff

Proof: We need to show that for points $x \ne y$ in $X$, there exist open sets $U,V$ in the topology $\tau'$ such that $x \in U, y \in V$, and $U \cap V$ is empty.

Since $\tau$ gives a Hausdorff topology, we can find open sets $U,V$ in the topology $\tau$, such that $x \in U, y \in V$ and $U \cap V$ is empty. And since $\tau'$ is finer than $\tau$, the sets $U,V$ satisfy the condition in $\tau'$ as well.