# Intersection between context-free and context-sensitive language decidability [closed]

I'm trying to find a formal proof of the following fact:

Given a context-free language, say $L_1$, and a context-sensitive language, say $L_2$, it is NOT decidable if their intersection is empty ($L_1 \cap L_2 = \emptyset$)

Some suggestions for the proof? Thanks

## closed as off-topic by Jeffε, KavehDec 28 '13 at 21:31

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Your question does not appear to be a research-level question in theoretical computer science. For more information about the scope, please see help center. Your question might be suitable for Computer Science which has a broader scope." – Jeffε, Kaveh
If this question can be reworded to fit the rules in the help center, please edit the question.

• This seems to be an undergraduate assignment level question and therefore is more suitable for Computer Science. – Kaveh Dec 27 '13 at 1:27
• This question has been reposted on Computer Science. – Gilles Dec 28 '13 at 16:22

• (It's also undecidable for a single context-sensitive language i.e. $L=\emptyset$) – sdcvvc Dec 26 '13 at 17:42