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Hi, I am having a doubt understanding the result of CFL – Regular:

Here’s my approach:

- CFL – Regular = CFL INTERSECTION Regular’ = CFL INTERSECTION Regular = CFL
- Suppose some CFL L1= {a^n b^n | n>=1} and some Regular R1= (a+b)* :

Now if I do CFL – Reg = {ab,aabb,aaabbb, ….} – { epsilon, a, b, ab, aabb, aaabbb, …..}

It gives { phi } which is Regular (hence also CFL)

So is it better to say CFL – Regular = Regular or CFL – Regular = CFL ? If both are separate options, which one should I go for? Thanks

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