# Is the intersection of two context free languages recursively enumerable?

I read a quotation attributed to Sheila Greibach that says that the intersection of two context free grammars is recursively enumerable.

I could not, however, find a citation for this quotation (and searching has failed to turn up a restatement of this result somewhere else).

Can anyone provide a proof or a citation to the original proof for this result? Can anyone state that it is false?

• It never fails that I find the result moments after posting ... The quotation with a citation is "To show this result, we rely on the well-known representation of recursively enumerable languages as the homomorphic image of the intersection of two context-free languages (Ginsburg et al., 1967)." but perhaps someone would like to go ahead and lay it out in an answer (I don't have that reference at hand) – Stephen Apr 16 '13 at 23:36
• No, I think it's perfect for cs.SE. – JeffE Apr 18 '13 at 21:16