P. Bracken et Am. Grundland, On the Backlund transformation and the theorem of permutability for the generalized Weierstrass system, INVERSE PR, 16(1), 2000, pp. 145-153
The connection between the structure of the second-order system describing
the Euclidean sigma-model equations associated with the generalized Weierst
rass system and the possibility of the construction of some classes of solu
tions is discussed. It is shown using the conditional symmetry method that
the auto-Backlund transformation (auto-BT) for the generalized Weierstrass
system can be constructed. The permutability theorem for this auto-BT is fo
rmulated. New classes of nonsplitting multisoliton solutions are obtained t
hrough the use of the theorem of permutability.