Past exam of the mathematics course of the University of Cambridge / 2025 / ii / Paper 2 / 20G / a / Solution

Let $K$ be a number field. The class group iswith multiplication induced by ideal multiplication. Equivalently, two fractional ideals $I,J$ represent the same class when $I=(\alpha )J$ for some $\alpha \in K^{\times }$.

Solved by gpt-5.6-sol high.