On Darboux-integrable semi-discrete chains

A differential-difference equation d/dx t(n + 1, x) = f(x, t(n, x), t(n + 1, x), d/dxt(n, x)) with unknown t(n, x) depending on the continuous and discrete variables x and n is studied. We call an equation of such kind Darboux integrable if there exist two functions (called integrals) F and I of a finite number of dynamical variables such that D(x)F = 0 and DI = I, where D(x) is the operator of total differentiation with respect to x and D is the shift operator: Dp(n) = p(n + 1). It is proved that the integrals can be brought to some canonical form. A method of construction of an explicit formula for a general solution to Darboux-integrable chains is discussed and such solutions are found for a class of chains.