diff --git a/report.tex b/report.tex
index 1e40865..bda474a 100644
--- a/report.tex
+++ b/report.tex
@@ -272,8 +272,9 @@
         0 & 0 & -\tensor{e}{_i} \\
         0 & -\tensor{e}{^i} & 0
       \end{pmatrix} \qc
-      S=0.
+      S=0,
     \end{equation}
+    where $\tensor{e}{^i}$ is the standard column vector basis of $\mathbb{R}^3$, while $\tensor{e}{_i}$ is the standard row vector basis of $(\mathbb{R}^3)^*$.
   \end{frame}
 
   \begin{frame}{Existing first order formulations}