Department of Applied Research,
Institute of Mathematics of NAS of Ukraine,
3 Tereshchenkivs'ka Str.,
01601 Kyiv-4, UKRAINE
E-mail: magda@imath.kiev.ua

Invariance of the quasilinear  equations of hyperbolic type  with respect to the four-parametric Lie algebras

We have completely solved the problem of description of quasi-linear hyperbolic-type differential equations in two independent variables that are invariant under four-parameter Lie groups.