diff --git a/Algo/Séminaire/Exercices sémaines.md b/Algo/Séminaire/Exercices sémaines.md
index 96ac770..dbd4566 100644
--- a/Algo/Séminaire/Exercices sémaines.md	
+++ b/Algo/Séminaire/Exercices sémaines.md	
@@ -107,14 +107,24 @@ val or_if: bool -> bool -> bool = <fun>
 
 
 (*logical implication*)
-if a && b then
-	true
-else if not a && b then
-	true
-else if not a && not b then
-	true
-else 
-	false
+# let imply_if a b =
+	if a then b
+	else true;;
+val imply_if: bool -> bool -> bool = <fun>
+
+(*logical exclusive or*)
+let xor a b = 
+	if a then
+		if b then false else true
+	else
+		if b then true else false
+
+(*logical equivalence = a b*)
+let equiv a b =
+	if a then b
+	else
+		if b then false else true (*not b*)
+
 ```
 
 ### Exercise 3.3