diff --git a/Concurrent Systems/notes/1b - Peterson algorithm.md b/Concurrent Systems/notes/1b - Peterson algorithm.md
index effd4cf..ae520e4 100644
--- a/Concurrent Systems/notes/1b - Peterson algorithm.md	
+++ b/Concurrent Systems/notes/1b - Peterson algorithm.md	
@@ -95,7 +95,8 @@ We say that: $p_i$ is at level $h$ when it exits from the $h$-th wait $\to$ a pr
 >[!info] What is the `wait` condition actually checking?
 >In the wait condition we check that all other processes are at a lower level.
 ##### MUTEX proof
-Lemma: for every $ℓ \in \{0,\dots,n-1\}$ , at most n-ℓ processes are at level ℓ, this implies MUTEX by taking ℓ = n-1
+>[!def] Lemma
+>For every $ℓ \in \{0,\dots,n-1\}$ , at most n-ℓ processes are at level ℓ, this implies MUTEX by taking ℓ = n-1
 
 Proof by induction on ℓ