Finished lecture 11.

src/op/c-star/order.tex

@@ -56,4 +56,10 @@
 \end{proof}
 
 
+\begin{definition}[Absolute Value]
+\label{definition:absolute-value-c-star}
+    Let $A$ be a $C^*$-algebra and $x \in A$, then $|x| = \sqrt{x^*x}$ is the \textbf{absolute value} of $x$. If $x$ is self-adjoint, then $|x| = 
+\end{definition}
+
+