The concept of improper gauge transformation, introduced originally by
Regge and Teitelboim, is used to analyse the constraint structure of
induced 2D-gravity, specifically in order to reveal the sl(2, R)) inva
riance. A local form of the induced action is taken by introducing an
auxiliary scalar field. The sl(2, R)) symmetry is shown to exist in a
gauge invariant way. It is shown how one can gauge fix the system to o
btain the quantum sl(2, R)) currents in the light cone gauge. Interest
ing connections between our local formulation with geometric quantizat
ion results are mentioned briefly. Some recent canonical formulations
of 2D-gravity have also been examined. (C) 1994 Academic Press, Inc.