diff --git a/Algo/CM/CM du 27 septembre.md b/Algo/CM/CM du 27 septembre.md
index 3486ad5..e3f873e 100644
--- a/Algo/CM/CM du 27 septembre.md	
+++ b/Algo/CM/CM du 27 septembre.md	
@@ -14,3 +14,9 @@
 	- A234
 
 ## Abstract Algebraic Data Types
+### Signature and hierarchy
+- a signature is composed by 
+	- a type (integer, stack, queue, graph)  
+	- an operations (name: profile)
+		- Exemple: ``insert: list x integer x element -> list``
+		- 
\ No newline at end of file