TOC grammar

Question

we know that for every RE language,there exist an unrestricted grammar...can we claim the opposite also??

(i.e for every Unrestcd grammar,there exist a RE)?

Comments

even non RE are unrestricted grammar.

So, converse is not always True

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can u give some example..

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What is meaning of unrestricted grammar

Means there is no bound.rt?

So, say  L(M) is regular

L(M) is infinite

all are non RE

Answer 1

That is not conversely true.

There are languages which are non recursively enumerable, unresrticyed grammer can be defined in any form or format to even specify those languages,

Consider this, if there is a non RE language, there will exist a grammer for it (by the definition of languages) but it cannot be claimed that language generated by a grammer is RE or non RE.

Its a membership problem for RE which is undecidable.