The BFV-formalism was introduced to handle classical systems, equipped with
symmetries. It associates a differential graded Poisson algebra to any
coisotropic submanifold S of a Poisson manifold (M,Π). However the
assignment (coisotropic submanifold) ⇝ (differential graded Poisson
algebra) is not canonical, since in the construction several choices have to be
made. One has to fix: 1. an embedding of the normal bundle NS of S into
M, 2. a connection ∇ on NS and 3. a special element Ω. We
show that different choices of the connection and Ω -- but with the
tubular neighbourhood fixed -- lead to isomorphic differential graded Poisson
algebras. If the tubular neighbourhood is changed too, invariance can be
restored at the level of germs.Comment: 21 pages; improved version, to appear in Pacific J. Mat