Reductions and conserved quantities for discrete compound KdV—Burgers equations

We present two methods to reduce the discrete compound KdV—Burgers equation, which are reductions of the independent and dependent variables: the translational invariant method has been applied in order to reduce the independent variables; and a discrete spectral matrix has been introduced to reduce the number of dependent variables. Based on the invariance of a discrete compound KdV—Burgers equation under infinitesimal transformation with respect to its dependent and independent variables, we present the determining equations of transformation Lie groups for the KdV—Burgers equation and use the characteristic equations to obtain new forms of invariants. (general)