Hamiltonian BRST-anti-BRST Theory
  The hamiltonian BRST-anti-BRST theory is developed in the general case of arbitrary reducible first class systems. This is done by extending the methods of homological perturbation theory, originally based on the use of a single resolution, to the case of a biresolution. The BRST and the anti-BRST generators are shown to exist. The respective links with the ordinary BRST formulation and with the $ sp(2) $-covariant formalism are also established. 
Philippe Gregoire and Marc Henneaux