Irreducible Hamiltonian BRST symmetry for reducible first-class systems
  An irreducible Hamiltonian BRST quantization method for reducible first-class systems is proposed. The general theory is illustrated on a two-stage reducible model, the link with the standard reducible BRST treatment being also emphasized. 
C. Bizdadea, E. M. Cioroianu, S. O. Saliu