Perturbations of APS Boundary Conditions for Lorentzian Dirac Operators
arXiv:2408.16696 · doi:10.3842/SIGMA.2025.088
Abstract
We study how far APS boundary conditions for a Lorentzian Dirac operator may be perturbed without destroying Fredholmness of the Dirac operator. This is done by developing criteria under which the perturbation of a compact pair of projections is a Fredholm pair.