Ace Test Series: Theory Of Computation - Decidablity

Question

 

 

Can someone explain this problem?

Comments

BASANT KUMAR

Information like input symbols, states,tape symbols are all included in the TM encoding. So to check if TM has less than 15 states or not we just need to check the encoding.

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If visiting a state problem will be decidable then the halting problem too will be decidable, which isn't true.

Answer should be A

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Because of   $"can" visit $,  $L_2$ is Decidable. If it was $"Visits \,\, or \,\, will \,\,visit"$, $L_2$ is State-entry problem and hence, Undecidable.

Only Ace can make a worthless question like this.