BRST-invariant algebra of constraints in terms of commutators and quantum antibrackets

We establish the general structure of the BRST-invariant algebra of constraints in its commutator and antibracket forms via the formulation of algebra-generating equations in a supplementally extended phase space. New ghost-type variables behave as fields and antifields with respect to quantum antibrackets. The explicit form of the BRST-invariant gauge algebra is given in detail for rank-one theories with a Weyland a Wick-ordered ghost sector. We construct a fixed-gauge unitarizing Hamiltonian and show that the formalism is physically equivalent to the standard BRST-BFV approach.