diff --git a/chapter01.tex b/chapter01.tex
index c6651d5..1968f6e 100644
--- a/chapter01.tex
+++ b/chapter01.tex
@@ -624,7 +624,7 @@ For example, in the above set
 New sets can be constructed using set operations:
 \begin{itemize}
 \item The \key{intersection} $A \cap B$ consists of elements
-that are both in $A$ and $B$.
+that are in both $A$ and $B$.
 For example, if $A=\{1,2,5\}$ and $B=\{2,4\}$,
 then $A \cap B = \{2\}$.
 \item The \key{union} $A \cup B$ consists of elements