Practice Question #5

Question

Let language L1 = {0,1}* if another language L2 is CFL.

L1 = empty set if another language L2 is not CFL.

L2 = a language the is R.E and its complement is R.E.

What can we say about L1 and L2?

is L1 and L2 are regular, CFL, CSL, R.E or finite or infinite.

Answer 1

L1 is regular since it can accept any number of 0's and 1's including epsilon

L2 is recurrsive  since L2 and L2'  both are RE

Comments

L1 is regular, this you obtained from the {0,1}* right??

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yeahh

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Then L1 is regular when L2 is CFL, A recursive L cannot be CFL,

I am confused here, can you please help me to understand?