diff --git a/chap-proofs.tex b/chap-proofs.tex
index aecfe80..c7df6cb 100644
--- a/chap-proofs.tex
+++ b/chap-proofs.tex
@@ -104,5 +104,8 @@ an attack is successful if the probability that it succeed is noticeable.
 \index{Negligible function}
 \textsc{Notation.} Let $f : \NN \to [0,1]$ be a function. The function $f$ is called \emph{negligible} if $f(n) = n^{-\omega(1)}$, and this is written $f(n) = \negl[n]$. Non-negligible functions are called \emph{noticeable} functions. And if $f = 1- \negl[n]$, $f$ is called \emph{overwhelming}.
 
+Once that we define the notions related to the core of the proof, we have to define the objects on what we work on.
+Namely, defining what we want to prove, and the hypotheses on which we rely.
+
 \section{Random-Oracle Model, Standard Model and Half-Simulatability}