diff --git a/header.tex b/header.tex
index 56efe89..7577c65 100644
--- a/header.tex
+++ b/header.tex
@@ -284,8 +284,8 @@
   placement=t,
   chapterlistsgaps=on,
 ]{exercisef}
-\newcounter{maxexercise} 
-\setcounter{maxexercise}{10000}  % show listings up to exercise maxexercise
+\newboolean{showexercisesolutions}
+\setboolean{showexercisesolutions}{true}
 \newenvironment{exercise}[2]%
 {\newcommand{\exercisesource}{#1}%
   \newcommand{\exercisefile}{\protect\StrSubstitute{#1}{_}{\_}}%
@@ -299,12 +299,12 @@
   }%
   {\hypersetup{hypertexnames=false}%
     \ifthenelse{\equal{\exercisesource}{}}{}%
-    {\ifthenelse{\value{exercisef}>\value{maxexercise}}{}%
+    {\ifthenelse{\boolean{showexercisesolutions}}%
       {\addtocounter{lstlisting}{-1}%
         \lstinputlisting[belowskip=0pt,aboveskip=1ex,nolol=true,title={\textbf{\tr{Solution}{L\"osung}:} \exercisefile}]{\codepath\exercisesource}%
         \ifthenelse{\equal{\exerciseoutput}{}}{}%
         {\addtocounter{lstlisting}{-1}%
-          \lstinputlisting[language={},title={\textbf{\tr{Output}{Ausgabe}:}},nolol=true,belowskip=0pt]{\codepath\exerciseoutput}}}}%
+          \lstinputlisting[language={},title={\textbf{\tr{Output}{Ausgabe}:}},nolol=true,belowskip=0pt]{\codepath\exerciseoutput}}}{}}%
     \hypersetup{hypertexnames=true}%
   \end{mdframed}%
   \renewcommand{\theenumi}{\saveenumi}}
diff --git a/pointprocesses/code/isiserialcorr.m b/pointprocesses/code/isiserialcorr.m
index ff97cfa..e5b07fb 100644
--- a/pointprocesses/code/isiserialcorr.m
+++ b/pointprocesses/code/isiserialcorr.m
@@ -26,7 +26,7 @@ function isicorr = isiserialcorr(isivec, maxlag)
         % plot:
         plot(lags, isicorr, '-b');
         hold on;
-        scatter(lags, isicorr, 10.0, 'b', 'filled');
+        scatter(lags, isicorr, 50.0, 'b', 'filled');
         hold off;
         xlabel('Lag k')
         ylabel('\rho_k')
diff --git a/pointprocesses/exercises/pointprocesses01.tex b/pointprocesses/exercises/pointprocesses01.tex
index dbc2a6c..1139ead 100644
--- a/pointprocesses/exercises/pointprocesses01.tex
+++ b/pointprocesses/exercises/pointprocesses01.tex
@@ -123,6 +123,7 @@ jan.benda@uni-tuebingen.de}
         pifouspikes = x.spikes;
         x = load('lifadapt.mat');
         lifadaptspikes = x.spikes;
+        clear x;
       \end{lstlisting}
     \end{solution}
 
@@ -195,4 +196,4 @@ jan.benda@uni-tuebingen.de}
   
 \end{questions}
 
-\end{document}
\ No newline at end of file
+\end{document}
diff --git a/pointprocesses/lecture/pointprocesses.tex b/pointprocesses/lecture/pointprocesses.tex
index f4b4f8d..22115b7 100644
--- a/pointprocesses/lecture/pointprocesses.tex
+++ b/pointprocesses/lecture/pointprocesses.tex
@@ -2,6 +2,8 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \chapter{Analyse von Spiketrains}
 
+\setboolean{showexercisesolutions}{false}
+
 \selectlanguage{ngerman}
 
 \determ[Aktionspotential]{Aktionspotentiale} (\enterm{spikes}) sind die Tr\"ager der
@@ -121,7 +123,7 @@ heisen die Intervalle auch \determ{Interspikeintervalle}
   berechnet.
 \end{exercise}
 
-\begin{exercise}{plotISIHist.m}{}
+\begin{exercise}{plotisihist.m}{}
   Schreibe eine Funktion, die die Histogrammdaten der Funktion
   \code{isiHist()} entgegennimmt, um das Histogramm zu plotten.  Im
   Plot sollen die Interspikeintervalle in Millisekunden aufgetragen
@@ -513,3 +515,5 @@ die Zellantwort mit dem STA verfaltet.
 \end{exercise}
 
 \selectlanguage{english}
+
+\setboolean{showexercisesolutions}{true}
diff --git a/pointprocesses/lecture/pointprocessscetchA.eps b/pointprocesses/lecture/pointprocessscetchA.eps
index cc32c7c..2dabb7f 100644
--- a/pointprocesses/lecture/pointprocessscetchA.eps
+++ b/pointprocesses/lecture/pointprocessscetchA.eps
@@ -1,7 +1,7 @@
 %!PS-Adobe-2.0 EPSF-2.0
 %%Title: pointprocessscetchA.tex
 %%Creator: gnuplot 4.6 patchlevel 4
-%%CreationDate: Mon Nov 27 21:08:10 2017
+%%CreationDate: Tue Nov 28 10:02:49 2017
 %%DocumentFonts: 
 %%BoundingBox: 50 50 373 135
 %%EndComments
@@ -430,10 +430,10 @@ SDict begin [
   /Title (pointprocessscetchA.tex)
   /Subject (gnuplot plot)
   /Creator (gnuplot 4.6 patchlevel 4)
-  /Author (jan)
+  /Author (benda)
 %  /Producer (gnuplot)
 %  /Keywords ()
-  /CreationDate (Mon Nov 27 21:08:10 2017)
+  /CreationDate (Tue Nov 28 10:02:49 2017)
   /DOCINFO pdfmark
 end
 } ifelse
diff --git a/pointprocesses/lecture/pointprocessscetchA.pdf b/pointprocesses/lecture/pointprocessscetchA.pdf
index 1aa1a36..c466889 100644
Binary files a/pointprocesses/lecture/pointprocessscetchA.pdf and b/pointprocesses/lecture/pointprocessscetchA.pdf differ
diff --git a/pointprocesses/lecture/pointprocessscetchB.eps b/pointprocesses/lecture/pointprocessscetchB.eps
index 68e83c4..04f8af1 100644
--- a/pointprocesses/lecture/pointprocessscetchB.eps
+++ b/pointprocesses/lecture/pointprocessscetchB.eps
@@ -1,7 +1,7 @@
 %!PS-Adobe-2.0 EPSF-2.0
 %%Title: pointprocessscetchB.tex
 %%Creator: gnuplot 4.6 patchlevel 4
-%%CreationDate: Mon Nov 27 21:08:10 2017
+%%CreationDate: Tue Nov 28 10:02:49 2017
 %%DocumentFonts: 
 %%BoundingBox: 50 50 373 237
 %%EndComments
@@ -430,10 +430,10 @@ SDict begin [
   /Title (pointprocessscetchB.tex)
   /Subject (gnuplot plot)
   /Creator (gnuplot 4.6 patchlevel 4)
-  /Author (jan)
+  /Author (benda)
 %  /Producer (gnuplot)
 %  /Keywords ()
-  /CreationDate (Mon Nov 27 21:08:10 2017)
+  /CreationDate (Tue Nov 28 10:02:49 2017)
   /DOCINFO pdfmark
 end
 } ifelse
diff --git a/pointprocesses/lecture/pointprocessscetchB.pdf b/pointprocesses/lecture/pointprocessscetchB.pdf
index ad9b8f9..fc3a365 100644
Binary files a/pointprocesses/lecture/pointprocessscetchB.pdf and b/pointprocesses/lecture/pointprocessscetchB.pdf differ
diff --git a/scientificcomputing-script.tex b/scientificcomputing-script.tex
index a470765..1e5fb9d 100644
--- a/scientificcomputing-script.tex
+++ b/scientificcomputing-script.tex
@@ -2,8 +2,6 @@
 
 \input{header}
 
-\setcounter{maxexercise}{1000}  % show listings up to exercise maxexercise
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{document}