First draft of L^1.

src/measure/lcg/modular.tex

@@ -42,8 +42,12 @@
     \end{align*}
 
     which contradicts the fact that $\lambda \ne 1$. Therefore $\lambda = 1$, and $\nu(dx) = \Delta_G(x^{-1})\mu(dx)$. 
-    
-    
 \end{proof}
 
+\begin{definition}[Unimodular]
+\label{definition:lcg-unimodular}
+    Let $G$ be a locally compact group, then $G$ is \textbf{unimodular} if $\Delta_G = 1$.
+\end{definition}
+
+