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seen Oct 29 at 11:05

Jan
15
comment Proving a language is not a CFL although it can be pumped
$a^{n-t}b^{n-s}c^n$ ? And using the fact that $t+s>0$ proves the whole thing? Actually you claim that $L$ can not be pumped for any partition of $w=uv^ixy^iz$ ?
Jan
14
comment Proving a language is not a CFL although it can be pumped
Are we speaking about the pumping lemma for CFL's? Because $vxy$ can be $a^tb^s$,$t+s \le n$ so $w$ can be pumped and nothing can be proved here, i am wrong?
Jan
14
comment Proving a language is not a CFL although it can be pumped
After further reading i realized it has to proven with Ogden's lemma. Still working on that..
Jan
14
comment Proving a language is not a CFL although it can be pumped
I know it will work, that is the tricky part because the easy way to prove a language is not a CFL is contradict the pumping lemma which can't be done it that case.
Jan
14
comment Are these languages context free or not?
What about $L_8$ and $L_9$ ? :)
Jan
14
comment Are these languages context free or not?
LOL!! can't believe someone from my class just copied paste the whole exercise :)) I currently stuck at 8&9
Jan
13
comment Finding an appropriate value to contradict the pumping lemma.
Thank you again..!
Jan
7
comment Formula for an equation
Can you please write the main idea behind the prove?
Dec
31
comment Decide if a formal language is a Context-free language
Isn't it enough to show that $L=h^{-1}(L_2)$ ? So $L$ is closed under inverse homomorphism? Why is the second part needed? Please be a bit more specific I am having bad time over here :)
Dec
29
comment Question about the meaning of expression in cryptography
So why $1^n$ and $0^n$ ? Why not other combinations?
Dec
29
comment Question about the meaning of expression in cryptography
The special role of $0^k$ and $1^k$ in that question
Dec
28
comment Question about the meaning of expression in cryptography
i know it represent a string of zeros or ones but why always in cryptography $1^k$ and $0^k$ are used? do they have a symbolic value? that the part that confuses me.