complement in 9.18

notes/3.md

@@ -16,8 +16,26 @@ An in-order traversal of the leaves is the original input.
 
 ### Ambiguity
 
-should be resolved
+should be removed
 
 for example: `A + B * C` should be resolved
 
+**removing ambiguity**
 
+
+### AST (Abstract Syntax Tree)
+
+
+### Error Handling
+
+One of the purposes of the compiler is error handling.
+- to detect non-valid programs
+- and to translate the non-valid to the valid
+
+## Parsing
+
+### Top-down Parsing
+
+**Recursive Descent Parsing**
+
+### Predictive Parsing