Formal Languages Questions
The main difference between a context-sensitive grammar and a recursively enumerable grammar lies in the restrictions imposed on the production rules.
A context-sensitive grammar is a formal grammar where the left-hand side of each production rule can have at most the same number of symbols as the right-hand side, and the context (surrounding symbols) must be preserved during the derivation. This means that the grammar can rewrite symbols based on the context in which they appear, allowing for more complex and specific rules.
On the other hand, a recursively enumerable grammar (also known as a type-0 grammar) has no restrictions on the production rules. It can rewrite symbols in any way, regardless of the context or the number of symbols involved. This makes recursively enumerable grammars more powerful and flexible, but also more difficult to analyze and work with.
In summary, the main difference is that context-sensitive grammars have restrictions on the number of symbols and the preservation of context, while recursively enumerable grammars have no such restrictions and can rewrite symbols in any way.