--- a/slides/slides12.tex	Thu Dec 03 13:46:18 2015 +0000
+++ b/slides/slides12.tex	Tue Jan 05 01:37:31 2016 +0000
@@ -81,6 +81,29 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
+\frametitle{Bitcoins for Real}
+
+\begin{itemize}
+\item you need a public-private key (the hash of the 
+public key to determines your bitcoin address) 
+
+\item if you want to receive bitcoins, you publicise 
+this address
+
+\item there are $2^{160}$ possibilities\\ 
+(no check for duplicates)\bigskip\pause
+
+\item transactions contain ``payment scripts''
+ (non-Turing-complete scripting language)\bigskip
+ 
+ \small simplest script: pay-to-public-key
+\end{itemize}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
 \frametitle{Bitcoin Keys}
 
 \begin{center}
@@ -349,8 +372,8 @@
 
 \small
 \[
-\bl{\begin{array}{@{}l@{}}\text{New}\\ \text{Difficulty}\end{array} \dn
-\begin{array}{@{}l@{}}\text{Old}\\ \text{Difficulty}\end{array} 
+\bl{\begin{array}{@{}l@{}}\text{New}\\ \text{Hardness}\end{array} \dn
+\begin{array}{@{}l@{}}\text{Old}\\ \text{Hardness}\end{array} 
 * \frac{\text{Actual time for the last 2016 blocks}}{20160}}
 \]
 
@@ -561,29 +584,6 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\begin{frame}[t]
-\frametitle{Bitcoins for Real}
-
-\begin{itemize}
-\item you need a public-private key (the hash of the 
-public key to determines your bitcoin address) 
-
-\item if you want to receive bitcoins, you publicise 
-this address
-
-\item there are $2^{160}$ possibilities\\ 
-(no check for duplicates)\bigskip\pause
-
-\item transactions contain ``payment scripts''
- (non-Turing-complete scripting language)\bigskip
- 
- \small simplest script: pay-to-public-key
-\end{itemize}
-
-\end{frame}
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
-
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
@@ -682,7 +682,8 @@
   (you cannot charge them back)\ldots{} bad luck
 
 \item you can send bitcoins to a ``non-existing'' address
-  (Mt.~Gox)
+  
+\item you send them to a script that can never be satisfied  
 \end{itemize}
 
 \end{frame}
@@ -715,6 +716,7 @@
 \begin{itemize}
   \item Don't gamble! I am not a first mover in such things.
   \item Cool idea, but I am sure there will be a Bitcoin~2.0.
+  (can for example mining pools force to be paid more?)
   \item It still depends on a lot of old-fashioned security 
   (e.g.~keeping private-keys secret)\bigskip