diff --git a/report.tex b/report.tex
index ebd0f4f..248e0df 100644
--- a/report.tex
+++ b/report.tex
@@ -172,7 +172,9 @@ interaction and composition operations, we have to somehow keep track of the
 parallel compositions that were used to reach this game: if the user wants to
 compose strategies on $A \strParallel B$ and $B \strParallel C$, we have to
 remember that those games were indeed parallel compositions of the right games,
-and not just a set where the events from, \eg, $A$ and $B$ are mixed.
+and not just a set where the events from, \eg, $A$ and $B$ are mixed. \\
+This information is kept in a tree, whose leaves are the base games that were
+put in parallel, and whose nodes represent a parallel composition operation.
 
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