Note on Backlund transformations

The method of obtaining Backlund transformations proposed by Chern and Tenenblat (1986) fits completely the approach of obtaining Backlund transformations by prolongation techniques. For KdV, MKdV and sine-Gordon equations the only difference consists in the application of a non-linear representation of the prolongation algebra other than the usual one. This representation can be obtained by a coordinate transformation of the prolongation variabl