The MacDowell–Mansouri action (named after S. W. MacDowell and Freydoon Mansouri) is an action that is used to derive Einstein's field equations of general relativity.
It can usefully be formulated in terms of Cartan geometry.
References
Further reading
Wise, D. (2010). "MacDowell-Mansouri gravity and Cartan geometry". Class. Quantum Grav. 27, 155010. Reid, James A.; Wang, Charles H.-T. (2014). "Conformal holonomy in MacDowell-Mansouri gravity". J. Math. Phys. 55, 032501.