Added motivation

latex/presentations/midterm/sections/theoretical_background.tex

@@ -8,8 +8,14 @@
 
 \begin{frame}[t]
     \frametitle{Motivation}
-
-    \todo{TODO}
+    \begin{itemize}
+        \item The general [ML] decoding problem for linear codes and the general problem
+            of finding the weights of a linear code are both NP-complete. \cite{ml_np_hard_proof}
+        \item The standard message-passing algorithms used for decoding [LDPC and turbo codes]
+            are often difficult to analyze. \cite{feldman_thesis}
+        \item The iterative message–passing algorithms preffered in practice do not guarantee
+            optimality and may fail to decode correctly when the graph contains cycles \cite{ldpc_conv}
+    \end{itemize}
 \end{frame}