Hi,
I have got following question:

Determine whether the following language is context free or not:
L = { w ϵ {a,b,c}*: na (w) = nb (w) = 2nc (w)}.

What is the meaning of "2nc" in the above question?

Zulfi.

 

Most likely nb(w) means the number of b's in w. If that's the case, wouldn't it make sense that 2nc(w) would mean two times the number of c's in w?

 

Hi,
Thanks a lot. If we first push 'a's and then we can equate with 'b's but we can't equate "2nc", so that language is not accepted by pda.

Is it okay?

Zulfi.

 

Hi,
Thanks a lot. If we first push 'a's and then we can equate with 'b's but we can't equate "2nc", so that language is not accepted by pda.

Is it okay?

Zulfi.

Depends on why you are claiming that we can't equate with the 2nc.

What if what was required was that na + nb = 2nc?

 

Hi,
Thanks for your reply.
<What if what was required was that na + nb = 2nc? >

In this case language is not accepted by npda.

Please reply the answer.

Zulfi.