2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34198In this report, which is an extended version of that appearing in the Proceedings of GR16, I will give a summary of the main topics covered in Session A.3. on mathematical relativity at GR16, Durban. The summary is mainly based on extended abstracts submitted by the speakers. I would like to thank all participants for their contributions and help with this summary.Extended version of report appearing in proceedings of GR16General Relativity and Quantum Cosmologytext