We explicitly construct the adjoint operator of coboundary operator and
obtain the Hodge decomposition theorem and the Poincar\'e duality for the Lie
algebra cohomology of the infinite-dimensional gauge transformation group. We
show that the adjoint of the coboundary operator can be identified with the
BRST adjoint generator Q† for the Lie algebra cohomology induced by
BRST generator Q. We also point out an interesting duality relation -
Poincar\'e duality - with respect to gauge anomalies and Wess-Zumino-Witten
topological terms. We consider the consistent embedding of the BRST adjoint
generator Q† into the relativistic phase space and identify the
noncovariant symmetry recently discovered in QED with the BRST adjoint N\"other
charge Q†.Comment: 24 pages, RevTex, Revised version submitted to J. Math. Phy