I am a little confused about exercise 1.2 in the book "Quantum Computation And Quantum Information" By Michael Nielson. The question is: Explain how a device which, upon input of one of two non-orthogonal quantum states |a> or |b> correctly identified the state, could be used to build a device which cloned the states |a> and |b>, in violation of no-cloning theorem. Conversely, explain how a device for cloning could be used to distinguish non-orthogonal quantum states. It asks us to explain how a device which upon input of one of two non-orthogonal quantum states correctly "identified" the state could be used to build a cloning device. What does "identify" mean? Does it mean, we know the exact state? Or does it mean we know it is state #1 vs state #2 but not the exact state? Second part asks us if we had cloning device how would we distinguish non-orthogonal quantum states. For that, can't we clone the state a large number of times and then measure them all to find the state, with error decreasing as no. of clones increases?