Group and renormgroup symmetry of a simple model for nonlinear phenomena in optics, gas dynamics, and plasma theory

Lie-Bنcklund symmetries of the quasi-Chaplygin system of equations are found as linear forms in hodograph variables. These symmetries are used to obtain invariant solutions and to construct a symmetry group of a boundary value problem (renormgroup). The implementation of an algorithm for solving the determining equations using the special package DIMSYM and the computer algebra system REDUCE is discussed.