Ain = {< M, w > |M accepts w without moving to a blank cell}

Show the problem above is decidable, semi-decidable, co-semi-decidable or is higher in the arithmetic hierarchy.

First rewrite the problem descriptions using quantifiers and verifiers (use VA, VR, VH for checking that a computation is accepting, rejecting and halting, respectively. )

Then prove that your intuition is correct;

You need to give an algorithm, and to prove that the problem is not in the class, give a reduction.