Nonlocal symmetries,consistent Riccati expansion integrability,and their applications of the (2+1)-dimensional Broer–Kaup–Kupershmidt system

For the (2+1)-dimensional Broer–Kaup–Kupershmidt(BKK) system, the nonlocal symmetries related to the Schwarzian variable and the corresponding transformation group are found. Moreover, the integrability of the BKK system in the sense of having a consistent Riccati expansion(CRE) is investigated. The interaction solutions between soliton and cnoidal periodic wave are explicitly studied.