diff --git a/semester4/ps/ps-rb/main.pdf b/semester4/ps/ps-rb/main.pdf
index 583031b..be1ce27 100644
Binary files a/semester4/ps/ps-rb/main.pdf and b/semester4/ps/ps-rb/main.pdf differ
diff --git a/semester4/ps/ps-rb/main.tex b/semester4/ps/ps-rb/main.tex
index e099109..32bf772 100644
--- a/semester4/ps/ps-rb/main.tex
+++ b/semester4/ps/ps-rb/main.tex
@@ -9,15 +9,18 @@
 
 \begin{document}
 \subtext{Basiert auf dem Skript von V. Tassion}
+\input{parts/00_prereq.tex}
+
+\newpage
 \section{Wahrscheinlichkeitsräume}
-\input{parts/00_intro.tex}
+\input{parts/01_basics.tex}
 
 \newpage
 \section{Zufallsvariablen}
-\input{parts/01_variables.tex}
+\input{parts/02_variables.tex}
 
 \newpage
 \section{Erwartungswert}
-\input{parts/02_expectation.tex}
+\input{parts/03_expectation.tex}
 
 \end{document}
diff --git a/semester4/ps/ps-rb/parts/00_prereq.tex b/semester4/ps/ps-rb/parts/00_prereq.tex
new file mode 100644
index 0000000..7821ad9
--- /dev/null
+++ b/semester4/ps/ps-rb/parts/00_prereq.tex
@@ -0,0 +1,7 @@
+\section*{Vorwissen}
+
+\definition \textbf{Geometrische Reihe}
+$$
+    s_n = a_1 \cdot \frac{1-q^n}{1-q} \qquad \underset{n\to\infty}{\lim} s_n = \frac{a_1}{1-q}
+$$
+\subtext{Wobei $a_i = a_1 \cdot q^{i-1}$}
\ No newline at end of file
diff --git a/semester4/ps/ps-rb/parts/00_intro.tex b/semester4/ps/ps-rb/parts/01_basics.tex
similarity index 98%
rename from semester4/ps/ps-rb/parts/00_intro.tex
rename to semester4/ps/ps-rb/parts/01_basics.tex
index 298fa38..a67c666 100644
--- a/semester4/ps/ps-rb/parts/00_intro.tex
+++ b/semester4/ps/ps-rb/parts/01_basics.tex
@@ -112,6 +112,10 @@ $$
     A, B \text{ unabhängig } \iffdef \P[A \cap B] = \P[A] \cdot \P[B]
 $$
 
+{\scriptsize
+    \notation $A\ \bot\ B \iffdef A,B$ unabhängig
+}
+
 \lemma \textbf{Äquivalente Aussagen zur Unabhängigkeit}
 
 \begin{tabular}{lll}
diff --git a/semester4/ps/ps-rb/parts/01_variables.tex b/semester4/ps/ps-rb/parts/02_variables.tex
similarity index 100%
rename from semester4/ps/ps-rb/parts/01_variables.tex
rename to semester4/ps/ps-rb/parts/02_variables.tex
diff --git a/semester4/ps/ps-rb/parts/02_expectation.tex b/semester4/ps/ps-rb/parts/03_expectation.tex
similarity index 100%
rename from semester4/ps/ps-rb/parts/02_expectation.tex
rename to semester4/ps/ps-rb/parts/03_expectation.tex
diff --git a/semester6/iml/main.pdf b/semester6/iml/main.pdf
index 032a0af..90bd2dc 100644
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