The document discusses the First Isomorphism Theorem from group theory. It states that if f is a homomorphism from group G to group H with image Im(f) and kernel ker(f), then the quotient group G/ker(f) is isomorphic to the image Im(f). As an example, it describes the complex numbers C* under multiplication as a group, and the function P that maps each element to its squared absolute value. P is a homomorphism with kernel equal to the unit circle. The quotient group C*/ker(P) is shown to be isomorphic to the positive real numbers under multiplication.