Question

2. Let L = {hMi: M is a Turing machine that accepts at least two binary strings}. a) Define the notions of a recognisable language and an undecidable language. [5 marks] b) Is L Turing-recognisable? Justify your answer with an informal argument. [5 marks] c) Prove that L is undecidable. (Hint: use Rice’s theorem.) [20 marks] d) Bonus: Justify with a formal proof your answer to b). [20 marks]

2. Let L-M M): M is a Turing machine that accepts at least two binary strings. a) Define the notions of a recognisable language and an undecidable language. [5 marks [5 marks] b) Is L Turing-recognisable? Justify your answer with an informal argument. c) Prove that L is undecidable. (Hint: use Rice's theorem.) [20 marks] 20 marks] d) Bonus: Justify with a formal proof your answer to b).

Answer 1

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