  The Polyakov's "soldering procedure" which shows how two-dimensional
diffeomorphisms can be obtained from SL(2,R) gauge transformations is discussed
using the free-field representation of SL(2,R) current algebra. Using this
formalism, the relation of Polyakov's method to that of the Hamiltonian
reduction becomes transparent. This discussion is then generalised to N=1
superdiffeomorphisms which can be obtained from N=1 super Osp(1,2) gauge
transformations. It is also demonstrated that the phase space of the Osp(2,2)
supercurrent algebra represented by free superfields is connected to the
classical phase space of N=2 superconformal algebra via Hamiltonian reduction.}
