TOC_Turing Machine

Question

Answer 1

Ans : C) L₁ $\cap$ L₂

Firstly input is fed to M₁ , if M₁ accepts input then it is fed to M₂. So, if both the machines accepts input then it says YES(accepted), otherwise NO.

Comments

Why not i/p apply to both Machine simultaneously then?

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Yes we can apply input to both the machines and take AND of YES

But

In this case, if the first machine rejects the input then we won't be feeding it to another machine, we can directly say whether string belongs to lang or not. It is just for efficiency.

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@ Kantikumar
I think it would be L1.L2 becoz of this sequential way of giving input.See in case of L1.L2 if M1 gives no i.e L1 not recursive then we can declare ans as no.We will go to M2 only if M1 provides yes.And No will be for M1 or M2.
Please check once