Einstein-Yang-Mills equations in the double null framework

We prove a semi-global gauge-invariant estimate for the solutions of the characteristic initial value problem associated with the coupled Einstein-Yang-Mills equations. In particular, we prove the existence of \textit{a} future development of regular initial data on a pair of incoming and outgoing null hypersurfaces emanating from a spacelike topological $2$-sphere. This marks the first study of the characteristic initial value problem of Einstein's equations with a non-linear source.