SYMMETRIES OF A CERTAIN PERIODIC CHAIN

摘要

We consider a periodic closure of a nonlinear integrable two-dimensional three-point chain. Integrability is understood in the sense that the chain admits a wide class of reductions, which are nonlinear hyperbolic Darboux integrable systems with two independent variables.We consider a system obtained as a period-2 periodic closure of one of two-dimensional three-point chains found within this framework. For this system, a second-order higher symmetry depending on two arbitrary functions is constructed.