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Math and science::Theory of Computation

Context-free languages: closed operations

Context-free language closure

If \( L \) and \( M \) are context-free languages, then the following are also context-free languages:

  • \( L \cup M \)
  • [operation 2]
  • [operation 3]

In other words, context-free languages are closed under union, [operation 2] and [operation 3].

There are important operations under which context free languages are not closed. Can you remember them?