Definition
Inherently Ambiguous Context-Free Language
A context-free language
is called inherently ambiguous if every context-free grammar that generates is ambiguous.
Examples
A context-free language with no unambiguous grammar
Consider the context-free language
with: Then
is context-free, but it is inherently ambiguous. A context-free grammar for
is: The word
has two different derivations, one via and one via .