diff --git a/symbols.tex b/symbols.tex
index dd442fe..0c89b8a 100644
--- a/symbols.tex
+++ b/symbols.tex
@@ -2,15 +2,16 @@
 \addcontentsline{toc}{chapter}{List of Symbols}
 
 \begin{tabular}{ll}
-  TM      & Turing Machine                       \\
-  $\ppt$  & Probabilistic Polynomial Time        \\
-  PKE     & Public Key Encryption                \\
-  ZK      & Zero-Knowledge                       \\
-  $\UC$   & Universal Composability              \\
-  $\SIS$  & Short Integer Solution               \\
-  $\LWE$  & Learning with Errors                 \\
-  $\SIVP$ & Shortest Independent Vectors Problem \\
-  $\DLP$  & Discrete Logarithm Problem           \\
-  $\DDH$  & Decisional Diffie-Hellman            \\
-  $\SXDH$ & Symmetric eXternal Diffie-Hellman
+  TM         &  Turing Machine                       \\
+  $\ppt$     &  Probabilistic Polynomial Time        \\
+  $\epsilon$ &  empty word                           \\
+  PKE        &  Public Key Encryption                \\
+  ZK         &  Zero-Knowledge                       \\
+  $\UC$      &  Universal Composability              \\
+  $\SIS$     &  Short Integer Solution               \\
+  $\LWE$     &  Learning with Errors                 \\
+  $\SIVP$    &  Shortest Independent Vectors Problem \\
+  $\DLP$     &  Discrete Logarithm Problem           \\
+  $\DDH$     &  Decisional Diffie-Hellman            \\
+  $\SXDH$    &  Symmetric eXternal Diffie-Hellman
 \end{tabular}