diff --git a/Algo/Séminaire/Chapter 3 - Case analysis.md b/Algo/Séminaire/Chapter 3 - Case analysis.md
index d6a71e8..103a466 100644
--- a/Algo/Séminaire/Chapter 3 - Case analysis.md	
+++ b/Algo/Séminaire/Chapter 3 - Case analysis.md	
@@ -17,4 +17,35 @@ if cond then expr1 else expr2
 # let abs(x) = 
 	if x>0 then x
 	else -x ;;;
+val abs : int -> int <fun>
+```
+
+## 3.2. Exceptions
+### Division by 0:
+```Ocaml
+# 1/0
+Exception : Division by zero
+```
+
+### Failwith:
+Failwith is a function that take a string argument (the reason) and return the error. That way, we can raise an error into our code
+```Ocaml
+# failwith;;
+-: string -> a = <fun>
+
+# failwith "oops";;
+Exception : Failwith "oops"
+```
+
+### invalid_arg:
+Invalid_arg is a function that take a string argument (the reason) and return the error. That way, we can raison an error about an argument
+```Ocaml
+# invalid_arg "oops";
+Exception: Invalid_argument "oops"
+
+(*example*)
+# let div a b = 
+	if b = 0 then invalid_arg("div: b = 0")
+	else a/b ;;;
+val div int -> int -> int = <fun>
 ```