Is equivalence of a CFG and an RG undecidable?

Question

I know that the equivalence of two context-free grammars is undecidable, but what about the equivalence of a regular grammar and a context-free grammar?

score 7 · Accepted Answer · answered Mar 04 '15 at 00:50

7

It is undecidable whether for a given CFG $G$, $L(G)=\Delta^*$, the set of all strings (over the terminal alphabet of $G$). That answers your question, by chosing the most simple regular grammar.

answered Mar 04 '15 at 00:50

Hendrik Jan

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Is equivalence of a CFG and an RG undecidable?

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