fix equation in prf:definition

mmcky · mmcky · commit ec2a8d6080d5 · 2024-03-18T14:49:02.000+11:00
diff --git a/lectures/inequality.md b/lectures/inequality.md
@@ -344,7 +344,7 @@ $$
 G :=
 \frac{\sum_{i=1}^n \sum_{j = 1}^n |w_j - w_i|}
      {2n\sum_{i=1}^n w_i}.
-$$ ()
+$$
 ```
 
 The Gini coefficient is closely related to the Lorenz curve.
