memoire-m2

diff --git a/sections/presentation.tex b/sections/presentation.tex
@@ -430,11 +430,11 @@ which is widely considered to the the standard presentation of
   then there is a presentation of \(\Mod(S_g)\) with generators \(a_0, \ldots
   a_{2g}\) subject to the following relations.
   \begin{enumerate}
-    \item The disjointness relations \([a_i, a_j] = 1\) for \(\alpha_i \cdot
-      \alpha_j = 0\).
+    \item The disjointness relations \([a_i, a_j] = 1\) for \(\alpha_i\) and
+      \(\alpha_j\) disjoint.
 
-    \item The braid relations \(a_i a_j a_i = a_j a_i a_j\) for \(\alpha_i
-      \cdot \alpha_j = 1\).
+    \item The braid relations \(a_i a_j a_i = a_j a_i a_j\) for \(\alpha_i\)
+      \(\alpha_j\) crossing once.
 
     \item The \(3\)-chain relation \((a_1 a_2 a_3)^4 = a_0 b_0\), where
       \[