diff --git a/chapter30.tex b/chapter30.tex
index 640f587..6fba32b 100644
--- a/chapter30.tex
+++ b/chapter30.tex
@@ -27,10 +27,10 @@ For example, the table
 \begin{tabular}{ccc}
 person & arrival time & leaving time \\
 \hline
-Uolevi & 10 & 15 \\
-Maija & 6 & 12 \\
-Kaaleppi & 14 & 16 \\
-Liisa & 5 & 13 \\
+John & 10 & 15 \\
+Maria & 6 & 12 \\
+Peter & 14 & 16 \\
+Lisa & 5 & 13 \\
 \end{tabular}
 \end{center}
 corresponds to the following events:
@@ -51,10 +51,10 @@ corresponds to the following events:
 \draw[fill] (5,-5.5) circle [radius=0.05];
 \draw[fill] (13,-5.5) circle [radius=0.05];
 
-\node at (2,-1) {Uolevi};
-\node at (2,-2.5) {Maija};
-\node at (2,-4) {Kaaleppi};
-\node at (2,-5.5) {Liisa};
+\node at (2,-1) {John};
+\node at (2,-2.5) {Maria};
+\node at (2,-4) {Peter};
+\node at (2,-5.5) {Lisa};
 \end{tikzpicture}
 \end{center}
 We go through the events from left to right
@@ -85,10 +85,10 @@ In the example, the events are processed as follows:
 \draw[fill] (5,-5.5) circle [radius=0.05];
 \draw[fill] (13,-5.5) circle [radius=0.05];
 
-\node at (2,-1) {Uolevi};
-\node at (2,-2.5) {Maija};
-\node at (2,-4) {Kaaleppi};
-\node at (2,-5.5) {Liisa};
+\node at (2,-1) {John};
+\node at (2,-2.5) {Maria};
+\node at (2,-4) {Peter};
+\node at (2,-5.5) {Lisa};
 
 \path[draw,dashed] (10,0)--(10,-6.5);
 \path[draw,dashed] (15,0)--(15,-6.5);
@@ -122,7 +122,7 @@ The symbols $+$ and $-$ indicate whether the
 value of the counter increases or decreases,
 and the value of the counter is shown below.
 The maximum value of the counter is 3
-between Uolevi's arrival time and Maija's leaving time.
+between John's arrival time and Maria's leaving time.
 
 The running time of the algorithm is $O(n \log n)$,
 because sorting the events takes $O(n \log n)$ time