1. The problem statement, all variables and given/known data How can irreducible representations of O(3) and SO(3) be determined from the irreducible representations of SU(2)? 3. The attempt at a solution I believe there is a two-one homomorphic mapping from SU(2) to SO(3); is that enough for some shared representations? If I had an idea of *why* irreducible reps. can determined for O(3) and SO(3) from SU(2), I might have a better notion of *how* to go about proving it. Cheers!