diff --git a/report.tex b/report.tex
index e92c068..169dc55 100644
--- a/report.tex
+++ b/report.tex
@@ -245,11 +245,11 @@
     \begin{equation}
       \pdvt{u^I} + \tensor{A}{^i^I_J} \pdv{u^J}{x^i} = S^I,
     \end{equation}
-    where both $A$ and $S$ can depend on $u^I$ but not their derivatives. For any unit covector $\xi_i$, the \emph{Principal symbol} matrix is defined as $P(\xi) := \tensor{A}{^i^I_J} \xi_i$.
+    where both $A$ and $S$ can depend on $u^I$ but not their derivatives. For any unit covector $\xi_i$, the \emph{Principal symbol} matrix is defined as $\tensor{P}{^I_J}(\xi) := \tensor{A}{^i^I_J} \xi_i$.
     The system is said to be:
     \begin{itemize}
-      \item \emph{weekly hyperbolic} if for any $\xi_i$, $P(\xi)$ has only real eigenvalues.
-      \item \emph{strongly hyperbolic} if for any $\xi_i$, $P(\xi)$ has only real eigenvalues and a complete set of eigenvectors, i.e., it is diagonalizable.
+      \item \emph{weekly hyperbolic} if for any $\xi_i$, $\tensor{P}{^I_J}(\xi)$ has only real eigenvalues.
+      \item \emph{strongly hyperbolic} if for any $\xi_i$, $\tensor{P}{^I_J}(\xi)$ has only real eigenvalues and a complete set of eigenvectors, i.e., it is diagonalizable.
       \item \emph{symmetrically hyperbolic} if there exists a positive definite symmetrizer matrix $H_{IJ}$ such that $H_{IK} \tensor{A}{^i^K_J}$ is symmetric for each $i$.
     \end{itemize}
   \end{frame}