Nonlocal symmetries and the nth finite symmetry transformation or AKNS system

In this paper, by introduction of pseudopotentials, the nonlocal symmetry is obtained for the Ablowitz-Kaup-Newell-Segur system, which is used to describe many physical phenomena in different applications. Together with some auxiliary variables, this kind of nonlocal symmetry can be localized to Lie point symmetry and the corresponding once finite symmetry transformation is calculated for both the original system and the prolonged system. Furthermore, the nth finite symmetry transformation represented in terms of determinant and exact solutions are derived.