Ambiguous Grammar


- Add disambiguous rules
- Rewrite the grammar
> - **Recursion Removal**
>> - Replace one of the recurisons with the base case
> - **Precedence Cascade**
>> - group operators of same precedence; write a different rule foreach precedence group



ambiguous grammar may always produce unique AST(but may produce different parse trees)
**Inessential Ambiguity** (okay)
- even for ambiguous grammar producing different ASTs
- Both carry the same semantics






