= (b) Use Rice's theorem to show that the set S5 = {(M): M is a TM that accepts [6 marks] at least five inputs} is undecidable. (c) Prove: Sy is recognisable (construct a recogniser for it). [4 marks] (d) Give the definition of the following concept: set A many-one reduces to set B. [3 marks] (e) Prove that Atm