Talk:Recursive grammar

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erhm[edit]

Another more obvious meaning would be for recursive instead of recursively enumerable languages. The current def is not actually cited. JMP EAX (talk) 09:23, 17 August 2014 (UTC)[reply]

What does it mean "if it contains production rules that are recursive"? Is S -> aSa recursive? Perhaps so. What about the grammar with two rules A -> aB and B -> Aa? JMP EAX (talk) 09:38, 17 August 2014 (UTC)[reply]

Also, the concept of leftmost derivation is not well defined above CFGs. JMP EAX (talk) 09:33, 17 August 2014 (UTC)[reply]

I see the this is another article "saved" at AfD by doing partial string matches versus random sources. JMP EAX (talk) 10:13, 17 August 2014 (UTC)[reply]

I first found the article when a wrong link in the Template:Formal languages and grammars had to be fixed: in line "Type-0, col. "Grammars", recursive grammar had to be corrected to unrestricted grammar; cf. Template_talk:Formal_languages_and_grammars#Removing "recursive grammar".

I considered to suggest the article recursive grammar for deletion, but changed my mind as it is of somewhat use at the lower end of the language hierarchy (cf. bottom line of the template, non-recursive grammar redirects to recursive grammar).

To define non-recursion formally, a strict partial order on the set of non-terminals would be required such that in each rule, each non-terminal on the lhs is strictly larger than each one on its rhs. Maybe, however, that notion doesn't make sense for grammars beyond context-free ones. - Jochen Burghardt (talk) 12:22, 17 August 2014 (UTC)[reply]

Except we want a reliable source to actually give this def and call it this, otherwise it's WP:OR. JMP EAX (talk) 13:40, 17 August 2014 (UTC)[reply]