A geometric interpretation of BRST symmetry

In a geometric and unified approach to gauge, (super)gravity and (super)string theories, all the symmetries are seen as diffeomorphisms along the directions of an appropriate group manifold G. The author shows how to incorporate BRST symmetry in this framework, by enlarging Lie (G) to contain a central fermionic generator Q, which satisfies Q²=0 and plays the role of the BRST charge.