Inner automorphisms, discrete and micklund transformations of integrable systems

It is shown that there exist two inner automorphisms and a discrete transformation besides the usual Backlund transformation for the integrable focusing nonlinear Schrodinger equation. By virtue of the inner automorphisms, the discrete transformation can generate multi-soliton solutions. The expressions for multi-soliton solutions generated by the discrete and the Backlund transformations turn out to be the same.