Undecidable Problems
Some questions that are undecidable for wider classes of grammars become decidable for context-free grammars; e.g. the emptiness problem (whether the grammar generates any terminal strings at all), is undecidable for context-sensitive grammars, but decidable for context-free grammars.
Still, many problems remain undecidable. Examples:
Read more about this topic: Context-free Grammar
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