2. Which is semi-decidable? One of the following sets is semi-decidable, and the other is not. Which is which? Give proofs for both. (a) {M | L(M) contains at least 481 clements} (b) {M | L(M)...

Extracted text: 2. Which is semi-decidable? One of the following sets is semi-decidable, and the other is not. Which is which? Give proofs for both. (a) {M | L(M) contains at least 481 clements} (b) {M | L(M) contains at most 480 elements} Hint: Recall that a set is decidable if and only if both it and its complement are semi-decidable. Use the contrapositive to show one of these is not semi-decidable. (Do not use Rice's Theorem in your proof.)