  To any non-trivial embedding of sl(2) in a (super) Lie algebra, one can
associate an extension of the Virasoro algebra. We realize the extended
Virasoro algebra in terms of a WZW model in which a chiral, solvable group is
gauged, the gauge group being determined by the sl(2) embedding. The resulting
BRST cohomology is computed and the field content of the extended Virasoro
algebra is determined. The (quantum) closure of the extended Virasoro algebra
is shown. Applications such as the quantum Miura transformation and the
effective action of the associated extended gravity theory are discussed in
detail.
