Past exam of the mathematics course of the University of Cambridge 2012 iii Paper 55 3 a Solution Created 2026-10-03 Updated 2026-10-07
Choose local sections related by , where . Keeping the same point of the principal bundle requires , so . For reconstruction of a principal connection from local gauge potentials, the local principal connection form transforms asUsing , computeandThe inhomogeneous terms cancel. Thus : both local expressions define the same one-form on the total space. This is compatibility across trivializations, whereas describes the separate right-action equivariance of a principal connection. In particular a change of trivialization is not an assertion that the local gauge potential of a principal connection itself is unchanged.