context-free language
a language is s context-free language if some context-free grammar recognizes it.
- closed under union
- closed under concatenation
- closed under closure
every regular language is a context-free language (a language defined by some cfg).
the space of regular languages is a subset of the space of context-free grammar languages.
-
is a context-free language. -
is a context-free language. -
is a non-context-free language.