typo

spaces/S000151/properties/P000138.md

@@ -5,7 +5,7 @@ value: false
 ---
 
 Fix $\theta\in[0,1]\setminus\mathbb Q$.
-Define a map on $X$ by the forumla:
+Define a map on $X$ by the formula:
 $f_\theta(x)=\begin{cases}\frac{x}{2}&\text{for }x<\theta,\\
 \frac{x+1}{2}&\text{for }x>\theta,\end{cases}\ x\in X$.