A context-free grammar is a restricted form of a [[Formal Grammar]] ---++ Closure Properties Context-free languages are closed under: * union * concatenation and these operations can thus be applied to context-free grammars. Context-free languages are not closed under: * intersection * complementation * set difference ---++ Parsing See [[Program Parsing]] for an overview of implementations. ---++ Resources * [[http://en.wikipedia.org/wiki/Context-free_grammar][Wikipedia]] * [[Syntax Definition]]